Allow midi playback in reverse

[Ecnassianer]

I wanted to create a scrubber that lets me skip forward and backwards through the music, then I realized there's no way for me to tell the midi processor to play backwards, or to skip to a specific time. I can set the playback speed higher to scrub forward (and with some tricksy math I could even skip forward a fairly specific amount of time in a single frame), but it doesn't seem like there's any way I can move backward other than restarting the midi from the beginning. It would be nice if I could play midi events backwards, and even nicer if it could flip the event on/offs so the sounds played in reverse too.