ruler: Show the hours and millis only if useful
timeline: Remove unuseful perspective logic
ui: Remove unused function
ruler: Use system font
ui: Remove unused class Point
prefs: Update pydoc and rename klass
tests: Move PreferencesDialog tests to test_prefs.py
tests: Move Project tests to test_project.py
medialibrary: Handle GnomeDesktop not available
render: Fix the video codec settings saving

Fixes bug https://bugzilla.gnome.org/show_bug.cgi?id=709536
check: Add GnomeDesktop as a soft dependency
check: Fix check_soft_dependencies to return what the caller expects
timeline: Rename Timeline to TimelineContainer
timeline: Move the toolbar logic to TimelineContainer

Also remove the standalone toolbar logic, to simplify the code.
timeline: Move UI data to xml file
timeline: Make the timeline toolbar and scrollbars background transparent
timeline: Rename for consistency
Use Gtk STYLE_CLASS constants for add_class
timeline: Be more strict when the project is loaded
cleanup