core: extend `core_select_lib` to be used for other libs than just
`kivy.core`
sdlttf: fix issue with cython/ios
activate sphinx.ext.viewcode (http://sphinx-doc.org/ext/viewcode.html)
add styling for viewsource link
doc: revisions to geometry.py, fixing broken links

Signed-off-by: Zen-CODE <zenkey.zencode@gmail.com>
doc: revisions to interactive.py
doc: fix spelling in interactive.py
Remove unproffesional language.

This has been proposed before, but the pull request was closed because it contained unrelated changes. See https://github.com/kivy/kivy/pull/1642
doc: fixed link to Clock, broke into two parts
doc :revisions to lang.py (1)
make auto dismiss of dropdown optional