'Ribbons' that are driven by audio loudness and tuned/draped for mask avatars

To enable, use developer->experimental->string hair
_loudness should be initialized to a known value rather than letting it inherit random bits from memory.

Looking through the code it appears that setLoudness() is always called right before update()... however there is a race condition when enabling hair... it might happen to be rendered before the simulation call..., which means the very first hair render frame might use the uninitialized value of _loudness to compute some colors.  I wonder what happens when NaN is injected into glColor values?