MarkManager 3.0.5 updated

Recreated everything that was working in 3.0.4
Corrected End of playback code

-Changed code in TimedSequenceEditorForm use Position.HasValue to detect
end of sequence instead of _context.  _context did not work if there was
no audio.
-added code to detect delay before playback actually starts.
General Housekeeping

Cleaned up remarked out code.  Adjusted general look of playback area.
Mark Manager: fixups after Chris' commits; mostly whitespace, and removing an unused fontDialog object. (VIX-232)
VixenApplication: don't allow multiple instances (VIX-234). Fix kindly provided by gizmohd.