Now using voxel-engine 0.14.0 with animated adjacent highlight transitions

I hope you don't mind me going a little crazy with this thing...

Updated to use voxel-engine 0.14.0 raycast results API (e.g. hit.voxel and hit.adjacent int arrays)

Also, when switching highlight from existing voxel to empty adjacent space (e.g. by pressing control key), the cube movement is slightly animated (only if opts.adjacentAnimate is true). A side benefit of this is that we are back to using a single mesh.

demo voxel-hello-world pull request to follow! thanks