MacGUI: Reworked a bit of HBPreviewController, the main differences are:
- CALayer instead of NSImageView, we don't need to center the layer manually, plus a lot of free animations.
- Reworked the scale to screen code, now it resize the window to the max size and then resize the picture layer, a bit simpler then before but the previous code had a weird issue were the window increased in size each time the slider changed until the control box was outside the window.
- Fixed an issue where the preview window would be unusable if it was closed while it was encoding a preview.
- Added a fEncodeState int to keep track of the encoding status like in HBController.
- Removed some unused code and variables. 
- The preview images are no longer 4px smaller than the said size.
- Added some nice image to the player controller.
- keyboard controls for the movie player.

git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@5230 b64f7644-9d1e-0410-96f1-a4d463321fa5