runMainLoop() now returns -1 if audio not set up so waitForMainLoop() is not called.  This allows scores with no audio at all to exit.
runMainLoop() now returns -1 if audio not set up so waitForMainLoop() is not called.  This allows scores with no audio at all to exit.

RTcmix/RTcmix,RTcmix/RTcmix,RTcmix/RTcmix,RTcmix/RTcmix,RTcmix/RTcmix,RTcmix/RTcmix