MacGui: Active Queue Initial Implementation

MacGui: Active Queue Initial Implementation
- Warning: currently, when adding jobs during encoding, the main window progress bar and task info gets hosed, if a workaround via libhb cannot be easily obtained, a cocoa workaround is available for checkin.
- Can now add jobs during encoding
- Scan progress bar is a barber pole until scanning progress during encoding is fine tuned.
- Needs further testing if DVD Auto Detect is turned on. If conflicts with drive arise, automatically turning off dvd auto detect when adding jobs during encoding is ready for checkin.

git-svn-id: svn://localhost/HandBrake/trunk@695 b64f7644-9d1e-0410-96f1-a4d463321fa5