[pitivi] (10 commits) ...Merge commit 'gnome/master'

[Edward Hervey <edwardrv src gnome org>]

Summary of changes:

  099aebd... really take into account the thumbnail aspect ratio
  9a7f64f... really take into account the thumbnail aspect ratio
  02818d8... also take pixel aspect ratio into account
  8e95168... Expose viewer API externally
  88c2857... viewer: add new method togglePlayback(), which also properl
  655b249... mainwindow: add accelerators for fullscreen, playpause, and
  2a579ac... sourcelist: wait until mouse-up to clear selection, if ever
  6f623e0... sourcelist: only call drag_begin at appropriate time, Final
  c3adbf4... mainwindow, timeline, viewer: keyboard seeking support
  726007e... Merge commit 'gnome/master'