Added support for "destructive" vs "non-destructive" voxel create
- changed VoxelTree to support destructive and non-destructive mode
- added protocol packet headers to differentiate
- added new UI to switch modes
- default mode now, non-destructive.
Merge pull request #312 from ZappoMan/master

support for "destructive" vs "non-destructive" createVoxel()
Merge branch 'master' of https://github.com/worklist/hifi

Conflicts:
	interface/src/Application.cpp