Full support of sysex for ttymidi

[cchaussat]

I have created this new version of ttymidi for my own needs but I took care of making it very general, not depending on any particular midi hardware nor software. I have tested it with alsa only, not with jack.
If you happen to test it, I am interested in getting your feedback on your usage context and on any issues you could get.

Present status :

• There is still one issue I could not understand nor solve : the specific FF 00 00 message created in ttymidi to display text and debug messages does not work well. Most of the times the text message does not print out completely if it is longer than ~ 10 bytes. By repeating the same call several times, eventually it prints out completely. Strange ... !? Fortunately, sysex messages work well both ways whatever the message length (tested up to 137 bytes with the midi file dump protocol). So I now use sysex instead of FF 00 00 also in order to pass text messages and debug traces from my specific midi hardware.

Have musical fun with ttymidi-sysex !