custom Color for midi clip

[Reaper10]

This goes with Better Color Handling #1665 adding a custom Color for midi clip option in gear menu. When a user picks a custom Color the midi notes in the piano roll window are the same custom Color as the midi clip Color.

[tresf]

Are you suggesting that the piano roll notes are the same color as the song editor or bb editor pattern? Since we don't have a way to change a piano roll color, this fall into an existing enhancement. Duplicate of #1160 and probably a bad idea out of the gate. Let's let colorization happen first, then we can decide if the piano roll notes should also be colored.

[Reaper10]

sorry didn't see that one.