Implemented and tested Seq sort functions
Implemented and tested Seq sort functions

Seq.SortVelocityIncreasing();
Seq.SortVelocityDecreasing();
Seq.SortRootNotatedPitchAscending();
Seq.SortRootNotatedPitchDescending();
These just call the corresponding function on all
the trks contained in the Seq.
Reorganised Seq.cs

notator/Moritz