Updated Greek translation
Updated Latvian translation
Transitions iconview signal reconected to signaling and pep fixes
help: Minor fix for figure references

Fixes bug 679397.
Update the clip's effect list when dragging onto the timeline
medialibrary: Properly use fallback icons

Fixes bug #679703
Prevent starting PiTiVi with an invalid project file argument

Fixes bug #679711
Add a preference for the default duration of image clips in the timeline

Fixes bug #679779
Disable keyboard shortcuts in the transformation spinbuttons
Updated Polish translation
Updated Spanish translation
Implement mockups
Integrate widgets in UI
Implement basic folding and add TwoStateButton
Correctly show audio and video controls
Create audio and video controls for each layer
Map controls to TimelineLayer
Reorder LayerControls by type

VideoControls are shown before AudioControls
Add some tooltips and remove wrong paddings
Remove unneeded TRACK_CONTROL_WIDTH