ENH: microphone.py now using sound.pyoSndServer

We can't have multiple pyo servers running at once. Deleted the
core.pyoServers list

Need to check whether the server is still being shut down properly when
this is done using __del__ (don't create extra pointers in microphone to
the pyoSndServer, just refer to sound.pyoSndServer!)

Removed the try...except...finally from the say_rgb demo