[sushi] (12 commits) ...mainwindow: bind the query_info_async callback

[Cosimo Cecchi <cosimoc src gnome org>]

Summary of changes:

  a985dfe... NULL terminate g_build_filename call (*)
  3c7fdbf... Use let, not const to import things in viewers (*)
  0469742... Import MimeHandler in all viewers (*)
  4834e88... Use the display name for the file name label (*)
  715e3ad... Put all clutter actors in a common group (*)
  9833645... Import gnome-shell tweener wrapper and add SUSHI_SLOWDOWN_F (*)
  8216018... Make opacity transitions on the uiGroup instead of individu (*)
  2a415f5... Handle non-utf8 filenames/basenames correctly (*)
  07042d2... Export close method on mainWindow (*)
  ececbac... Track the currently visible file in the main window (*)
  893e934... Add closeIfAlreadyShown argument to ShowFile (*)
  e017ad1... mainwindow: bind the query_info_async callback

(*) This commit already existed in another branch; no separate mail sent