Add OrbitControls script, World class controls attributes and setControls method

Controls on mouse click and drag don't work yet.  It just braks and the blocks
disappear.  I'll have to start debugging and figure out what's missing.
* Fix scripts on index.html to get OrbitControl library correctly.
* Implement rudimentary click-and-drag camera control
* Still to come, make movement smoother.
Reduce size of blocks cloud.
  * Created fewer blocks
  * Drew back camera perspective
  * Reduced randomness of block placement
Remove unnecessary setControls function
Merge pull request #5 from jonathanpeterwu/mouse-move-camera

Mouse move camera