optimized distanceToCamera() added distanceToPoint() and distanceSquaredToPoint()
Merge branch 'master' of https://github.com/worklist/hifi into render_voxels_optimization
Merge pull request #292 from Ventrella/master

Headotomy (made head its own class to prepare for future development)
Merge pull request #294 from ZappoMan/render_voxels_optimization

Optimized distanceToCamera()