MacGui: Integrate Source Scanning into Main Window and permanently disable DVD Drive...

MacGui: Integrate Source Scanning into Main Window and permanently disable DVD Drive Auto Detect
- Choose DVD directly if necessary out of the Browse window
- No longer use sheets to show scan progress
- Added Scan Progress bar under Source section of main window
- Removed the "Browse" button in source section in anticipation of a "Source" icon in Toolbar
- For now, use File -> Select Source in Main Menu to get a new source (used to be "Select DVD"). Note: this is the same as 0.7.1
- Removed disable dvd auto detect from the prefs nib

git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@742 b64f7644-9d1e-0410-96f1-a4d463321fa5