allow avatar agents to ask for audio loopback
removed Oculus Manager from camera object, using _tightness = 0.0 to shutoff camera movement smoothing
Fixed acceleration checking bug that was limiting angular rotation, changed mouselook to work correctly/stable.
Added sensor fusion for more stable gyro roll, pitch.
Merge branch 'master' of https://github.com/worklist/hifi
Merge pull request #492 from birarda/synthesis

add STK library and a distance based reverb effect
Merge branch 'master' of github.com:worklist/hifi into echo
Fixes per code review.
add missing cstring include for memcpy
merge fixes
Merge pull request #491 from PhilipRosedale/master

Sensor fusion for more stable gyros, camera tightness 0 option
conditional cleanup in Agent to re-fire PRB
Merge pull request #493 from birarda/echo

add back audio echo option
Merge branch 'master' of github.com:worklist/hifi into synthesis