Fix build errors in docs

[KeyWeeUsr]

~31 errors purged to 2:

p4a\doc\source\commands.rst:17: WARNING: autodoc: failed to import class u'ToolchainCL' from module u'toolchain'; the module executes module level statement and it might call sys.exit().
p4a\doc\source\recipes.rst:488: WARNING: autodoc: failed to import class u'Recipe' from module u'toolchain'; the module executes module level statement and it might call sys.exit().

Most of the errors came with ext/sphinx_rtd_theme because it used non-existing math extension. Then some broken links, underlines, missing _static etc.

I took out ext/* part of the docs out because it's just an example from sphinx and shouldn't be available in the final documentation. It isn't included in pdf or in the website, but if you build a local docs, then it'll be there.

[inclement]

Great, thanks. I've gone further and removed the 'related' doc page, since it wasn't really worth the space.

[KeyWeeUsr]

I wasn't really sure about removing it, so I left it there, hehe.