Switch to newer openstackdocstheme and reno versions

Switch to openstackdocstheme 2.2.1 and reno 3.1.0 versions. Using
these versions will allow especially:
* Linking from HTML to PDF document
* Allow parallel building of documents
* Fix some rendering problems

Update Sphinx version as well.

Change pygments_style to 'native' since old theme version always used
'native' and the theme now respects the setting and using 'sphinx' can
lead to some strange rendering.

openstackdocstheme renames some variables, so follow the renames
before the next release removes them. A couple of variables are also
not needed anymore, remove them.

See also
http://lists.openstack.org/pipermail/openstack-discuss/2020-May/014971.html

Change-Id: I420adfab0ff40fffd9a211d72ad6c953a495676e

doc/requirements.txt

@@ -2,10 +2,10 @@
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
 
-sphinx!=1.6.6,!=1.6.7,>=1.6.2 # BSD
+sphinx>=2.0.0,!=2.1.0 # BSD
 sphinxcontrib-apidoc>=0.2.0  # BSD
-openstackdocstheme>=1.18.1 # Apache-2.0
-reno>=2.5.0 # Apache-2.0
+openstackdocstheme>=2.2.1 # Apache-2.0
+reno>=3.1.0 # Apache-2.0
 mock>=2.0.0 # BSD
 ddt>=1.0.1 # MIT
 testtools>=2.2.0 # MIT

doc/source/conf.py

@@ -27,6 +27,7 @@ import os
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
 # ones.
 extensions = [
+    'openstackdocstheme',
     'sphinx.ext.autodoc',
 ]
 
@@ -46,14 +47,10 @@ master_doc = 'index'
 project = u'freezer-web-ui'
 copyright = u'2016, OpenStack'
 
-# 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 short X.Y version.
-version = '1.2'
-# The full version, including alpha/beta/rc tags.
-release = '1.2.0'
+# General information about the project.
+openstackdocs_repo_name = 'openstack/freezer-web-ui'
+openstackdocs_bug_project = 'freezer'
+openstackdocs_bug_tag = 'doc'
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
@@ -85,7 +82,7 @@ exclude_patterns = []
 #show_authors = False
 
 # The name of the Pygments (syntax highlighting) style to use.
-pygments_style = 'sphinx'
+pygments_style = 'native'
 
 # A list of ignored prefixes for module index sorting.
 #modindex_common_prefix = []

lower-constraints.txt

@@ -41,7 +41,7 @@ requests==2.18.4
 rfc3986==1.1.0
 rjsmin==1.0.12
 snowballstemmer==1.2.1
-Sphinx==1.6.2
+Sphinx==2.0.0
 sphinxcontrib-websupport==1.0.1
 stevedore==1.28.0
 termcolor==1.1.0

test-requirements.txt

@@ -8,7 +8,7 @@ coverage!=4.4,>=4.0 # Apache-2.0
 oslo.config>=5.2.0 # Apache-2.0
 testrepository>=0.0.18 # Apache-2.0/BSD
 testtools>=2.2.0 # MIT
-sphinx!=1.6.6,!=1.6.7,>=1.6.2  # BSD
+sphinx>=2.0.0,!=2.1.0 # BSD
 astroid==2.1.0 # LGPLv2.1
 pylint==2.3.1 # GPLv2