Added parameter directions to function parameter documentation.

Added new experimental FAST_STREAM_FUNCTIONS compile time option to speed up stream transfers at the expense of a higher FLASH consumption (needs testing to verify improved throughput).

MIDI device demo no longer blocks if a note change event is sent while the endpoint is not ready.

Move new Class Driver powered demos to a new ClassDriver subdirectory, re-add old low level demos to a LowLevel subdirectory.