Supervoxel example updates

Added better messages to explain single camera transform, fixed bug where negative Z values were always abs'd, even if transform disabled.
Added ability to use normals provided within point cloud, and ability to disable this.
Adjusted visualization so voxels and supervoxels are displayed better.
Cleaned up command line parsing.
I thought about it, but didn't include it because of those files we encountered a while back where people were putting points at (0,0,0) instead of nan. log(z) "converts" those points to nans =)