#1 fix tied note issue in abc2midi

[Benjamin Ketcham]

If the last note on a staffline ends with a tie,
abc2midi would miss the target note on the next line,
instead playing two distinct notes.

The fix of the symptom is to remove all references to
the variables tied_sum and tied_denom in
store.c:dotie(). I don't really understand why this
helps! Someone who knows the code should carefully
re-examine the logic in that area. Hopefully this at
least gets you pointed in a useful direction.