Merge pull request #183 from ZappoMan/render_voxels_optimization

Render voxels optimization
Changed avatar.h to store _distanceToNearestAvatar
Merge pull request #185 from PhilipRosedale/master

Improvement to other avatar detection to help jeffrey's merge
Merge branch 'master' of https://github.com/worklist/hifi into render_voxels_optimization