Performance modifications to make the application more responsive during loading and playback of files.

Plugged a few minor memory leaks

Implemented pLinq (Task Parallel Library) in places to boost performance
Deprecated Extensions.cs NotNull function because it was causing unnecessary overhead.   By just using .Where(x => x != null) it saved 25% in load time and overall performance increased
Cut editor load time in half when loading new sequence by stopping the resizing of each row while adding.  Resizing is then done when all rows are completed
Fix formatting in TSE form code: entirely superficial changes.
Remove debug message on sequence load.