patch for midi.scm applied to 2.6.1

[Stephen]

Yeah!

I was just about to try one more time to get it right by using Lite Edit 1.1 
to remove the Windows line endings before invoking diff -u rather than add 
the line endings to the existing source and ask someone to remove the line 
endings from the patch as a final touch in learning how to do this thing 
right when I decided that of course I need to apply the patch to a newer 
version of Lilypond, checked Lilypond 2.6.1 and realized it had already been 
applied.

Thanks.

Stephen