MacGui: moved the HBQueueOutlineView class to its own file.

git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@6539 b64f7644-9d1e-0410-96f1-a4d463321fa5
MacGui: switched the Preview window class from NSPanel to NSWindow.

git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@6540 b64f7644-9d1e-0410-96f1-a4d463321fa5