converted bools to int for melody convergence/splitting
required notes are now stored in a hash set
got rid of note-optional pair, just compare to RequiredNotes
Revert "converted bools to int for melody convergence/splitting"

This reverts commit 332da2ef77193277b19c46dd8f6958df2aa27ce5.
Changed to one bool - MelodySplittingAndConvergenceAllowed
cleanup