Some fixes and extra bits for the midi stuff; makes things much more
* icon and .desktop get installed properly
* much more graceful handling of jackd shutdowns
* midi thread will now try and use SCHED_FIFO. If you run jackd with
jackstart (or as root, but you don't want to do that :) then you
don't need to do anything to enable this as jackd will give the
appropriate rights to jack rack.