Updated Polish translation
Make the dogtail tests work again with the Clutter timeline, cleanup code
mainwindow: Ensure "Clip properties" is the focused context tab on startup
previewers: Use proper debug statements instead of prints for the thumbnailer

Also rename some internal variables
previewers: General code cleanup
Updated Spanish translation
bin: Make it possible to source pitivi-git-environment
script: Add option to force autogen of modules
timeline: Removing an effect should not trigger graphical updates.
bin: Make it possible to run a command right after running pitivi-git
bin: disable docbook if disabling docs in pitivi-git
bin: Do not change directory if sourced or launching a command

+Rework the way we set PS1
Clarify a bit the comments
Remove unused variable
Set MODULES_CORE in a single place
Show info about up to date packages
Always build local pygobject and gobject-introspection
Calm down test_system_gnome
Add back missing Timeline.purgeObject
Add some missing imports in timeline.py