Update AUTHORS to match the About dialog
Remove the ABOUT-NLS file, it's completely useless
Remove the pitivi.spec file

This file has not been updated in six years, is awkward to maintain and was
certainly not used by RPM packagers: they have much better spec files already.
Refactor check.py for faster, better (simpler), stronger dependency checking

Run the checks before initializing and importing any modules;
Remove many translatable strings that are redundant or not meant for users;
Update dependencies to reflect the current requirements of PiTiVi.
Specify the dependencies version requirements in only one place (check.py)

Also update the README file to be more future-proof
Simplify the _in_devel() convenience methods
Simplify application.py by merging the GuiPitivi and FullGuiPitivi classes
depsmanager: Refactor the code a little bit to be more pythonic
render: Use " " instead of italics in the render complete notification
Updated Polish translation
Updated Spanish translation
Updated Slovenian translation
Fix test_*.py files not being included in the release.

The bug was introduced in commit 8908ee01a77046bd02872bd479045bc5176f8ddd.
Updated Russian translation
[l10n] Updated Italian translation.
Updated Brazilian Portuguese translation reviewed by Enrico Nicoletto <liverig@gmail.com>
Updated Serbian translation
effects: Make effect property setting working again
loggable: Implement a FIXME log level
bin: Update the git-environment to use GES overrides