[Stk] updates

[Gary P. Scavone]

Hi everyone,

You may or may not have noticed that I recently released new versions  
of both RtMidi and RtAudio.  The RtAudio fixes concern UNICODE  
support for the Windows DirectSound API, as well as MinGW compiler  
support for the ASIO API.  The RtMidi fixes concern sysex message  
support in the Windows MM API, as well as the addition of an optional  
virtual port argument with the openVirtualPort() functions.

I've updated the STK download page (http://ccrma.stanford.edu/ 
software/stk/download.html) with links for the new files.  There was  
also a fix reported for the demo.cpp program concerning channel  
assignments.  I've updated the demo.cpp file and linked that as well.

Happy Stk-ing.

--gary