MacGui: Default Presets Initial Implementation

MacGui: Default Presets Initial Implementation
- Allows user to set a given preset as a default which will be used upon launch. As well, if user has not specified a preset as the default, HB will use the "HB - Normal" Built-in Preset at launch.
- Added the "Make Default" button at the bottom of the Presets Drawer.
- Default Preset is shown in Bold in the Presets Drawer
- Added a Select Default Preset command to the "Presets" Menu in the Menu Bar.
-- Note: the buttons and other display stuff is not set in stone, once again, initial function over form on intitial implementation.

git-svn-id: svn://localhost/HandBrake/trunk@764 b64f7644-9d1e-0410-96f1-a4d463321fa5