MacGui: Queued item editing initial implementation.

MacGui: Queued item editing initial implementation.
- Sends a chosen queued item back to the main window for reload ( and rescan ) via contextual menu (right click)
- Deletes queued item from queue after being reloaded to main window ( after editing or whatever, send back to queue via Add To Queue Button same as a new source).
- New queue window contextual menu also includes delete and show options previously only available via separate icons.
- Note: Needs testing particularly in the subtitle area, which is not to say there aren't other bugs.

git-svn-id: svn://localhost/HandBrake/trunk@3080 b64f7644-9d1e-0410-96f1-a4d463321fa5