Some of the examples still need to be updated to reflect changes in master.
* Rename the various example_theme extensions with a leading 0, e.g.
* Add v03_jinja, this example was previously inline in the docs, move into
a working and testable extension, update the docs to include it.
Note that this means all the following versions of the example extension
are renamed, as their version numbers are bumped.
* Update setup.py.
* css.rst: Update literalinclude's.
* static-files.rst: Update literalinclude's and images.
* templates.rst, substitutions.rst: Update literalinclude's, various tweaks
and improvements. Add screenshot of debug footer.