qextserial library is no longer maintained, suggest we move
to this library, also greater chance for thread safety,
library now builds in cmake, will add Serial2 sources to
handle the new qserial, should easily plug into serial interface
now.

Switched from flite for speech on the Mac to built-in MacOSX speech synthesizer. Fixed build system for 64-bit builds (using official SDL.framework, and Qt frameworks).