Drag support for adding/removing (as well as coloring) voxels.  I had to
ensure that the "last" voxel edited was the one under the cursor after the
operation, not the one operated on.
Merge branch 'master' of https://github.com/worklist/hifi
Added toggle for voxel textures; they may be slowing some machines down.
Merge branch 'master' of https://github.com/worklist/hifi
Merge branch 'master' of https://github.com/worklist/hifi
I believe the problem with voxel rendering is caused by the update thread's
writing the data while the render thread is attempting to read it.  This
should fix the issue.
Tweak: let the reader know when it needs to load the full VBO.
Merge pull request #360 from ey6es/master

Dragging support for adding/deleting voxels, toggle for voxel noise texture, fix for threading issue with voxels (believe this is what caused the bad triangles).