Need to disambiguate from video stream messages

I don't think it's needed anywhere in QGC since this has been a bug for a long time.

Remove isnan() and isinf() templates from QGC.h for Windows builds, this
generates errors (already defined in math.h).

Broke windows compilation.

Add debug output for when voice initialization fails on Windows

Removed or annotated existing commented-out code

Clean up logic for saying emergency text.

Previous code didn't properly check for if speech was enabled.

Some functionality was lost, will need to be fixed in a later commit.

To include OpenGL primitives, we include the QtOpenGL header instead, which has all the platform-specific includes taken care of for us.