Added alphaTest to hills
Ken McClure:  animated the quadcopter.dae model to fly up 3m for a second or two and then to fly 30m up after that.
Ken McClure:  Update to rover tracks.  Lowered the floating tracks section to be along the ground.  Also updated the rocks and boulder placement near the end track and mini rover position.
Merge pull request #392 from virtual-world-framework/Ken-Art

Ken McClure:  Update to backdrop.dae.  Broke the object into 8 pieces to...