removed VoxelSystem::createSphere() which was dead code
removed addRandomSphere() which was dead code
update TREE_SCALE to 128 so it's power of 2, and MAX_VOXELS_PER_SYSTEM to 500k
dead code cleanup
Tweaks to createSphere() plus some new helper functions
- changed createSphere() to support new NATURAL mode which uses perlin
  noise to create natural color and shape
- added getVoxelCount()
- coding standard cleanup
added SceneUtils.h/.cpp which moves addSphereScene() to a common location
dead code cleanup
code cleanup, new scene
Fixed a couple bugs in pointToVoxel()
- fixed a byte packing bug related to having exactly 7 bits of octal data
  where we weren't correctly packing the last bit and moving the byte count
  forward. This resulted in bogus colors being written
- fixed a bug for points that exactly match an octet boundary test creating
  voxels that are one a unit smaller than they should be