First round of settings serialization.  Setup an API to load and save different settings to the avatar data file.
Initial serialized settings:
Gyro look
Mouse look
Transmitter drives
Voxel rendering
Voxel textures
Star rendering
Atmosphere rendering
Avatar rendering
Oculus rift mode
Render stats
Frame stats
Look at vectors
Logging
Frustum debugging
View frustum offset
Camera frustum
Setup various debug options.
Documentation for #19308.
Store settings in an ordered map to allow for runtime getting and setting of settings.  Read the setting file on startup, then write on shut down.
Check how many matches were found for the given data type we're checking for.  1 for bool and float, 3 for vec3.  Return false and assign default values if this isn't true.
add --local option to avatar-mixer
Coding standard cleanup based upon ZappoMan's suggestions.
Merge branch 'master' of https://github.com/worklist/hifi into 19308
tune the distance attenuation on audio-mixer
Merge pull request #461 from birarda/master

distance attenutation tuning on audio mixer
more tuning on distance attenuation for audio mixer
Merge pull request #462 from birarda/master

distance attenutation tuning for audio-mixer
tune distance attenuation
Merge pull request #463 from birarda/master

distance attenuation tuning
update last heard from time for audio injectors
Merge pull request #465 from birarda/master

stop continous killing of audio injectors
Massive changes to orientations: use quaternions rather than Orientation
class.
Merge branch 'master' of https://github.com/worklist/hifi into reorient

Conflicts:
	interface/src/Avatar.cpp
Moved direction vectors to AvatarData, made them align with OpenGL view space
(to avoid the 180 degree rotations).
Moved gravity influence multiplier into constant, reduced.