Update stringed macro.
- make single string instrument work with midi-poly-player.
- add documentation string for the generated stringed instruments.
Create single string instrument "ektara" & midi-poly-player example in comments.
Add now+ fn to eliminate most "late" messages.
Merge pull request #206 from rogerallen/rallen-string-1

Update stringed macro, add midi-poly-player compatible stringed instrument.