fix small build issue in voxel-edit
Merge pull request #846 from ZappoMan/master

fix small build issue in voxel-edit
implement threaded voxel processing
enabled Low Res sending while moving by default
make voxel fade shorter elapsed time and logarithmic instead of linear
Merge pull request #847 from ZappoMan/master

voxel sending/processing improvements
Merge branch 'master' of https://github.com/worklist/hifi into bugfixes
Merge pull request #848 from ZappoMan/bugfixes

make voxel fade shorter elapsed time and logarithmic instead of linear
Merge branch 'master' of https://github.com/worklist/hifi into glow
Render to texture first, rather than copying from the frame buffer.  Copying
from the frame buffer requires it to have an alpha channel, which actually
does something on OS X (meaning we have to set it to 1.0).  We're going to
want to render to texture anyway for SSAO (or other effects).