Docs: Typos and minor highlights in formats
Docs: Changes in po format

* Rearranged items
* Splitted items
* Added examples
* Removed broken link
* Removed section
* Merged sections
Docs: Include in styleguide how to break long strings
Docs: Added section about imports to styleguide

[ci skip]
Docs: add label to allow cross-reference
Add l10n guide as intersphinx resource and add link
Actually run unit test for optrecurse

py.test will not "collect" a class for testing if it has __init__ method,
even if it otherwise matches the necessary patterns:
http://pytest.org/latest/goodpractises.html#conventions-for-python-test-discovery
Prevent import exceptions in Sphinx autodocs

add Mock()ed PyLucene and provide its VERSION
add support of ElementTree.fixtag in Mock for xmlwrapper
don't raise ImportError for cPO/fPO if no gettext PO library found
Don't confuse pytest with build/ copies of tests

also skip docs and .git to speed tree-walk (nothing there to import anyhow)