build: rename `sphinx_build.py` to `sphinx.py`

Change-Id: Ieea421a7a9c0d8710aee8be6dabaf6e90f1720fc
diff --git a/.waf-tools/doxygen.py b/.waf-tools/doxygen.py
index 18b3292..6948194 100644
--- a/.waf-tools/doxygen.py
+++ b/.waf-tools/doxygen.py
@@ -24,9 +24,8 @@
 			bld(features="doxygen", doxyfile='Doxyfile', ...)
 """
 
-from fnmatch import fnmatchcase
-import os, os.path, re, stat
-from waflib import Task, Utils, Node, Logs, Errors, Build
+import os, os.path, re
+from waflib import Task, Utils, Node
 from waflib.TaskGen import feature
 
 DOXY_STR = '"${DOXYGEN}" - '
@@ -204,8 +203,8 @@
 	conf.find_program('doxygen', var='DOXYGEN', mandatory=False)
 	conf.find_program('tar', var='TAR', mandatory=False)
 
-# doxygen docs
+# doxygen command
 from waflib.Build import BuildContext
 class doxy(BuildContext):
-    cmd = "doxygen"
-    fun = "doxygen"
+    cmd = 'doxygen'
+    fun = 'doxygen'
diff --git a/.waf-tools/sphinx_build.py b/.waf-tools/sphinx.py
similarity index 92%
rename from .waf-tools/sphinx_build.py
rename to .waf-tools/sphinx.py
index 3666d5a..f538977 100644
--- a/.waf-tools/sphinx_build.py
+++ b/.waf-tools/sphinx.py
@@ -1,5 +1,7 @@
 # inspired by code by Hans-Martin von Gaudecker, 2012
 
+"""Support for Sphinx documentation"""
+
 import os
 from waflib import Node, Task, TaskGen, Utils
 
@@ -34,8 +36,8 @@
     node.sig=Utils.h_file(node.abspath())
 
 
-@TaskGen.feature("sphinx")
-@TaskGen.before_method("process_source")
+@TaskGen.feature('sphinx')
+@TaskGen.before_method('process_source')
 def apply_sphinx(self):
     """Set up the task generator with a Sphinx instance and create a task."""
 
@@ -80,11 +82,12 @@
 
 
 def configure(conf):
+    """Check if sphinx-build program is available."""
     conf.find_program('sphinx-build', var='SPHINX_BUILD', mandatory=False)
 
 
-# sphinx docs
+# sphinx command
 from waflib.Build import BuildContext
 class sphinx(BuildContext):
-    cmd = "sphinx"
-    fun = "sphinx"
+    cmd = 'sphinx'
+    fun = 'sphinx'