Fix roll lane lengths

[mtolly]

A very small issue: the roll lane notes on pitches 126 and 127 should have their note-off event a very small amount of time (a few MIDI ticks) after the note-on of the last note in the roll. This was discussed in a Rock Band Creators forum thread, and is recommended by Harmonix authors as the right way to get a good-looking result in-game.

[mtolly]

Now that I think about it, this should probably be done by a program. Having the manually positioned note-off event in the input MIDI is a bit ugly, and a program could consistently adjust it to be in the correct position during the build process.