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/README.md b/README.md
index b9ca240..19dff9c 100644
--- a/README.md
+++ b/README.md
@@ -1,35 +1,38 @@
-NLSR - Named Data Link State Routing Protocol
-=============================================
+# NLSR: Named Data Link State Routing Protocol
+
+![Language](https://img.shields.io/badge/C%2B%2B-14-blue.svg)
+[![Build Status](https://travis-ci.org/named-data/NLSR.svg?branch=master)](https://travis-ci.org/named-data/NLSR)
+![Latest Version](https://img.shields.io/github/tag/named-data/NLSR.svg?color=darkkhaki&label=latest%20version)
 
 For complete documentation and more extensive information,
-please visit the [NLSR homepage](http://named-data.net/doc/NLSR/current/).
+please visit the [NLSR homepage](https://named-data.net/doc/NLSR/current/).
 
-If you are new to the NDN community of software generally, read the
-[Contributor's Guide](https://github.com/named-data/NFD/blob/master/CONTRIBUTING.md).
+If you are new to the NDN software community, please read the
+[Contributor's Guide](https://github.com/named-data/.github/blob/master/CONTRIBUTING.md)
+to get started.
 
 ## Overview
 
-NLSR is a routing protocol in NDN that populates NDN's Routing Information Base. NLSR
-will continue to evolve alongside the Named Data Networking [protocol](http://named-data.net/doc/ndn-tlv/).
+NLSR is a routing protocol in NDN that populates NDN's Routing Information Base.
+NLSR will continue to evolve alongside the Named Data Networking
+[protocol](https://named-data.net/doc/NDN-packet-spec/current/).
 
-NLSR is an open and free software package licensed under the GPL 3.0 license and free to all
-Internet users and developers.  For more information about the licensing details and
-limitations, refer to [COPYING.md](https://github.com/named-data/NLSR/blob/master/COPYING.md).
+NLSR is an open and free software package licensed under the GPL 3.0 license and free to
+all Internet users and developers.  For more information about the licensing details and
+limitations, refer to [`COPYING.md`](COPYING.md).
 
 NLSR is developed by the members of the [NSF-sponsored NDN project team](https://named-data.net/project/participants/).
-For more details, please refer to [AUTHORS.md](https://github.com/named-data/NLSR/blob/master/AUTHORS.md).
-Bug reports and feedback are highly appreciated and can be made through the
-[Redmine site](https://redmine.named-data.net/projects/nlsr).
+For more details, please refer to [`AUTHORS.md`](AUTHORS.md).
+Bug reports and feedback are highly appreciated and can be made through our
+[Redmine site](https://redmine.named-data.net/projects/nlsr/issues).
 
-The main design goal of NLSR is to provide a routing protocol to populate NDN's FIB.
+The main design goal of NLSR is to provide a routing protocol to populate NDN's RIB.
 NLSR calculates the routing table using link-state or hyperbolic routing and produces
 multiple faces for each reachable name prefix in a single authoritative domain. NLSR
 will continue to evolve over time to include neighbor discovery and to become a full
 fledged inter-domain routing protocol for NDN.
 
-
-Source releases
----------------
+## Source releases
 
 The source code and source-code installation instructions are always available at
 the following links:
@@ -38,13 +41,12 @@
 - [Getting Started with NLSR](https://named-data.net/doc/NLSR/current/GETTING-STARTED.html)
 - [GitHub NLSR repository](https://github.com/named-data/NLSR)
 
-Additional information
-----------------------
+## Additional information
 
-- [Contributor's Guide](https://github.com/named-data/NFD/blob/master/CONTRIBUTING.md)
+- [Contributor's Guide](https://github.com/named-data/.github/blob/master/CONTRIBUTING.md)
 - [NLSR Wiki](https://redmine.named-data.net/projects/nlsr/wiki/)
 - Feature requests and bug reports are welcome on our
-  [NLSR on NDN Redmine](https://redmine.named-data.net/projects/nlsr)
+  [NLSR on NDN Redmine](https://redmine.named-data.net/projects/nlsr/issues)
 - [NLSR Mailing List Sign Up](https://listserv.memphis.edu/scripts/wa.exe?GETPW1)
 - [NLSR Mailing List](https://listserv.memphis.edu/scripts/wa.exe?SUBED1=NLSR-HELP-L&A=1)
 - [NLSR Mailing List Archives](https://listserv.memphis.edu/scripts/wa.exe?A0=NLSR-HELP-L)