Fix some crashing issues on delete

- added a mutex in voxel-server to make sure we're not deleting and sending nodes at the same time since these run on separate threads
- moved clearDirtyBit() for node to above potential deletion
- made collapsing of empty tree optional and not called in the client, since that is not needed there, only called in server where it's useful
- made reaverageVoxelColors() optional based on if the VoxelTree needs to do that. The server one will, but by default, trees do no reaverage their colors
- new animations that are NOT YET ENABLED