staffLines now correctly imported into music21
Merge remote-tracking branch 'upstream/master' into StaffLines

Conflicts:
	music21/converter.py
staffLines export to MusicXML is done
Small change for displaying Layout data.
More PY3 changes and MultiprocessTest
more PY3 improvements
Merge remote-tracking branch 'upstream/master' into StaffLines
accidently removed subConverter.py
del obsolete. more py3 fixes
python3 multiprocess test WORKS!
Merge remote-tracking branch 'upstream/master' into StaffLines
Release version v1.9.3.
Release version v.1.9.3
Initial 2.0 commit
few changes for PyPi
Revert to 1.9.3 version -- will do 2.0 as a separate branch.
quarterLength selectively produces Fractions
optional Fractions almost everywhere
added chordify test
all offsets etc. are rational or power of 2 floats

Speed reduction is less than 1%.  Made up in test suite by optimizing
abc/translate.