Ongoing issues with sound files on NXTs

[jramboz]

I'm continuing to see performance issues with custom sound fonts on NXTs. I'm putting this here to track the ongoing issues and to document my attempts to fix them.

[jramboz]

Forgot to tag commits, but mostly I've been working on tweaking the timing factor for non-Windows uploads. I think this is an underlying driver difference between Windows and Mac/Linux. Windows works fine without any additional delay factor, but Mac/Linux just writes in a continuous stream as fast as it can to NXTs unless I manually delay it. I've settled into a delay of 0.000087 seconds between bytes, since this should be the transmission time of one byte on a 115200 baud connection. It actually leads to slightly slower speeds than I get on Windows, but seems so far to be stable.