Updated Polish translation
Updated Slovenian translation
Updated Spanish translation
python: explicitly use python2
timeline: fix missing import

fix following exception:

Traceback (most recent call last):
  File "/usr/lib/pitivi/python/pitivi/timeline/timeline.py", line 1197,
in _dragLeaveCb
    GLib.timeout_add(75, self._dragCleanUp, context)
NameError: global name 'GLib' is not defined
python: change missing python2 shebangs
track: fix runtime warning

 RuntimeWarning: Expecting to marshal a borrowed reference for <Pixbuf
object at 0x44f7a00 (GdkPixbuf at 0x4880000)>, but nothing in Python is
holding a reference to this object. See:
https://bugzilla.gnome.org/show_bug.cgi?id=687522
Updated Brazilian Portuguese translation
mainwindow: Use unicode characters directly in the title string

Avoid using Python2's unicode string method,
as our source code has a header indicating it's unicode anyway

This prevents tracebacks that block startup on locales such as Russian
Fixes bug #697775
Updated Czech translation
Port to the new little API changes in GES

GES.TimelineLayer has been renamed GES.Layer
The rate property of GES.TimelineLayer.add_asset has been removed
Begins the integration of the new ClutterTimeline
Make the ruler update only on zoom stopped
Make the ruler update only on scroll stopped
Various performance improvements to the timeline clip thumbnailer

- Create thumbnails in the background (even when not visible at the moment)
- Draw only visible thumbnails, respect the clip's in-point
- Prioritize visible thumbnails over background thumbnail generation
- Use JPEG compression for thumbnails
- Scale the thumbnail in the pipeline instead of doing it manually
Improve clip thumbnailing performance when scrolling/zooming the timeline
Only commit clip thumbnails once they're done processing
Subclass TimelineElement in ClipElement and TransitionElement
Fix the handling of title clips in the timeline
Make actions sensitive on selection changed