build+ci: switch to python3

Also in this commit:
 * Sync CI scripts with other projects
 * Modernize docs/conf.py
 * Replace redmine_issue extension with sphinx.ext.extlinks
 * Minor updates to docs/doxygen.conf.in
 * Cleanup README.md and INSTALL.rst

Refs: #5095
Change-Id: I614e876e6aed73659f4f4cea01813f4604599263
diff --git a/docs/conf.py b/docs/conf.py
index 68de944..050d44c 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -1,37 +1,53 @@
 # -*- coding: utf-8 -*-
 #
-# NLSR - Named Data Link State Routing Protocol documentation build configuration file, created by
-# sphinx-quickstart on Sun Apr  6 19:58:22 2014.
+# Configuration file for the Sphinx documentation builder.
 #
-# This file is execfile()d with the current directory set to its
-# containing dir.
-#
-# Note that not all possible configuration values are present in this
-# autogenerated file.
-#
-# All configuration values have a default; values that are commented out
-# serve to show the default.
+# This file only contains a selection of the most common options. For a full
+# list see the documentation:
+# http://www.sphinx-doc.org/en/master/config
 
-import datetime
-import sys
-import os
+# -- Path setup --------------------------------------------------------------
 
 # If extensions (or modules to document with autodoc) are in another directory,
 # add these directories to sys.path here. If the directory is relative to the
 # documentation root, use os.path.abspath to make it absolute, like shown here.
-sys.path.insert(0, os.path.abspath('.'))
+#
+# import os
+import sys
+# sys.path.insert(0, os.path.abspath('.'))
 
-# -- General configuration ------------------------------------------------
+
+# -- Project information -----------------------------------------------------
+
+project = u'Named Data Link State Routing Protocol (NLSR)'
+copyright = u'Copyright © 2014-2020 Named Data Networking Project.'
+author = u'Named Data Networking Project'
+
+# The short X.Y version
+#version = ''
+
+# The full version, including alpha/beta/rc tags
+#release = ''
+
+# There are two options for replacing |today|: either, you set today to some
+# non-false value, then it is used:
+#today = ''
+# Else, today_fmt is used as the format for a strftime call.
+today_fmt = '%Y-%m-%d'
+
+
+# -- General configuration ---------------------------------------------------
 
 # If your documentation needs a minimal Sphinx version, state it here.
-#needs_sphinx = '1.0'
+#
+needs_sphinx = '1.1'
 
 # Add any Sphinx extension module names here, as strings. They can be
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
 # ones.
 extensions = [
+    'sphinx.ext.extlinks',
     'sphinx.ext.todo',
-    'redmine_issue'
 ]
 
 def addExtensionIfExists(extension):
@@ -39,218 +55,88 @@
         __import__(extension)
         extensions.append(extension)
     except ImportError:
-        sys.stderr.write("Extension '%s' in not available. "
+        sys.stderr.write("Extension '%s' not found. "
                          "Some documentation may not build correctly.\n" % extension)
-        sys.stderr.write("To install, use \n"
-                         "  sudo pip install %s\n" % extension.replace('.', '-'))
 
-# sphinxcontrib.googleanalytics is currently not working with the latest version of sphinx
-# if os.getenv('GOOGLE_ANALYTICS', None):
-#     addExtensionIfExists('sphinxcontrib.googleanalytics')
-
-# Add any paths that contain templates here, relative to this directory.
-templates_path = ['_templates']
-
-# The suffix of source filenames.
-source_suffix = '.rst'
-
-# The encoding of source files.
-#source_encoding = 'utf-8-sig'
+addExtensionIfExists('sphinxcontrib.doxylink')
 
 # The master toctree document.
 master_doc = 'index'
 
-# General information about the project.
-project = u'NLSR - Named Data Link State Routing Protocol'
-copyright = u'2014-{}, Named Data Networking Project'.format(datetime.date.today().year)
-
-# The version info for the project you're documenting, acts as replacement for
-# |version| and |release|, also used in various other places throughout the
-# built documents.
-
-# The language for content autogenerated by Sphinx. Refer to documentation
-# for a list of supported languages.
-#language = None
-
-# There are two options for replacing |today|: either, you set today to some
-# non-false value, then it is used:
-#today = ''
-# Else, today_fmt is used as the format for a strftime call.
-#today_fmt = '%B %d, %Y'
+# Add any paths that contain templates here, relative to this directory.
+templates_path = ['_templates']
 
 # List of patterns, relative to source directory, that match files and
 # directories to ignore when looking for source files.
+# This pattern also affects html_static_path and html_extra_path.
 exclude_patterns = []
 
-# The reST default role (used for this markup: `text`) to use for all
-# documents.
-#default_role = None
 
-# If true, '()' will be appended to :func: etc. cross-reference text.
-#add_function_parentheses = True
-
-# If true, the current module name will be prepended to all description
-# unit titles (such as .. function::).
-#add_module_names = True
-
-# If true, sectionauthor and moduleauthor directives will be shown in the
-# output. They are ignored by default.
-#show_authors = False
-
-# The name of the Pygments (syntax highlighting) style to use.
-pygments_style = 'sphinx'
-
-# A list of ignored prefixes for module index sorting.
-#modindex_common_prefix = []
-
-# If true, keep warnings as "system message" paragraphs in the built documents.
-#keep_warnings = False
-
-
-# -- Options for HTML output ----------------------------------------------
+# -- Options for HTML output -------------------------------------------------
 
 # The theme to use for HTML and HTML Help pages.  See the documentation for
 # a list of builtin themes.
-# html_theme = 'default'
+#
 html_theme = 'named_data_theme'
 
-# Theme options are theme-specific and customize the look and feel of a theme
-# further.  For a list of options available for each theme, see the
-# documentation.
-#html_theme_options = {}
-
 # Add any paths that contain custom themes here, relative to this directory.
-html_theme_path = ['./']
-
-# The name for this set of Sphinx documents.  If None, it defaults to
-# "<project> v<release> documentation".
-#html_title = None
-
-# A shorter title for the navigation bar.  Default is the same as html_title.
-#html_short_title = None
-
-# The name of an image file (relative to this directory) to place at the top
-# of the sidebar.
-#html_logo = None
-
-# The name of an image file (within the static path) to use as favicon of the
-# docs.  This file should be a Windows icon file (.ico) being 16x16 or 32x32
-# pixels large.
-#html_favicon = None
+html_theme_path = ['.']
 
 # Add any paths that contain custom static files (such as style sheets) here,
 # relative to this directory. They are copied after the builtin static files,
 # so a file named "default.css" will overwrite the builtin "default.css".
 html_static_path = ['_static']
 
-# Add any extra paths that contain custom files (such as robots.txt or
-# .htaccess) here, relative to this directory. These files are copied
-# directly to the root of the documentation.
-#html_extra_path = []
 
-# If not '', a 'Last updated on:' timestamp is inserted at every page bottom,
-# using the given strftime format.
-#html_last_updated_fmt = '%b %d, %Y'
-
-# If true, SmartyPants will be used to convert quotes and dashes to
-# typographically correct entities.
-#html_use_smartypants = True
-
-# Custom sidebar templates, maps document names to template names.
-#html_sidebars = {}
-
-# Additional templates that should be rendered to pages, maps page names to
-# template names.
-#html_additional_pages = {}
-
-# If false, no module index is generated.
-#html_domain_indices = True
-
-# If false, no index is generated.
-#html_use_index = True
-
-# If true, the index is split into individual pages for each letter.
-#html_split_index = False
-
-# If true, links to the reST sources are added to the pages.
-#html_show_sourcelink = True
-
-# If true, "Created using Sphinx" is shown in the HTML footer. Default is True.
-#html_show_sphinx = True
-
-# If true, "(C) Copyright ..." is shown in the HTML footer. Default is True.
-#html_show_copyright = True
-
-# If true, an OpenSearch description file will be output, and all pages will
-# contain a <link> tag referring to it.  The value of this option must be the
-# base URL from which the finished HTML is served.
-#html_use_opensearch = ''
-
-# This is the file name suffix for HTML files (e.g. ".xhtml").
-html_file_suffix = ".html"
-
-# Output file base name for HTML help builder.
-htmlhelp_basename = 'nlsr-docs'
-
-
-# -- Options for LaTeX output ---------------------------------------------
+# -- Options for LaTeX output ------------------------------------------------
 
 latex_elements = {
-# The paper size ('letterpaper' or 'a4paper').
-#'papersize': 'letterpaper',
+    # The paper size ('letterpaper' or 'a4paper').
+    #
+    # 'papersize': 'letterpaper',
 
-# The font size ('10pt', '11pt' or '12pt').
-#'pointsize': '10pt',
+    # The font size ('10pt', '11pt' or '12pt').
+    #
+    # 'pointsize': '10pt',
 
-# Additional stuff for the LaTeX preamble.
-#'preamble': '',
+    # Additional stuff for the LaTeX preamble.
+    #
+    # 'preamble': '',
+
+    # Latex figure (float) alignment
+    #
+    # 'figure_align': 'htbp',
 }
 
 # Grouping the document tree into LaTeX files. List of tuples
 # (source start file, target name, title,
 #  author, documentclass [howto, manual, or own class]).
 latex_documents = [
-  ('index', 'nlsr-docs.tex', u'NLSR - Named Data Link State Routing Protocol Documentation',
-   u'Named Data Networking Project', 'manual'),
+    ('index', 'nlsr-docs.tex', u'Named Data Link State Routing Protocol (NLSR)',
+     author, 'manual'),
 ]
 
-# The name of an image file (relative to this directory) to place at the top of
-# the title page.
-#latex_logo = None
 
-# For "manual" documents, if this is true, then toplevel headings are parts,
-# not chapters.
-#latex_use_parts = False
-
-# If true, show page references after internal links.
-#latex_show_pagerefs = False
-
-# If true, show URL addresses after external links.
-#latex_show_urls = False
-
-# Documents to append as an appendix to all manuals.
-#latex_appendices = []
-
-# If false, no module index is generated.
-#latex_domain_indices = True
-
-
-# -- Options for manual page output ---------------------------------------
+# -- Options for manual page output ------------------------------------------
 
 # One entry per manual page. List of tuples
 # (source start file, name, description, authors, manual section).
 man_pages = [
-    ('manpages/nlsr', 'nlsr', u'Named Data Link State Routing Protocol Daemon', None, 1),
-    ('manpages/nlsr.conf', 'nlsr.conf', u'Named Data Link State Routing Protocol Daemon config file', None, 5),
-    ('manpages/nlsrc', 'nlsrc', u'Command-line utility to interact with and collect statistics from NLSR', None, 1),
+    ('manpages/nlsr',      'nlsr',      u'Named Data Link State Routing daemon', None, 1),
+    ('manpages/nlsr.conf', 'nlsr.conf', u'Named Data Link State Routing daemon configuration file', None, 5),
+    ('manpages/nlsrc',     'nlsrc',     u'command-line utility to interact with and collect statistics from NLSR', None, 1),
 ]
 
-
 # If true, show URL addresses after external links.
-#man_show_urls = False
+#man_show_urls = True
 
-if os.getenv('GOOGLE_ANALYTICS', None):
-    googleanalytics_id = os.environ['GOOGLE_ANALYTICS']
-    googleanalytics_enabled = True
 
-redmine_project_url = "https://redmine.named-data.net/"
+# -- Custom options ----------------------------------------------------------
+
+doxylink = {
+    'nlsr': ('NLSR.tag', 'doxygen/'),
+}
+
+extlinks = {
+    'issue': ('https://redmine.named-data.net/issues/%s', 'issue #'),
+}