Addresses chetan51/nupic.cerebro2#26

Added camera controls to position camera in various default views. As a part of this, added an equation to calculate a reasonable distance for the camera based on the size of the model. All of this necessitated some modifications to the display of the dat.GUI elements in order to make room for the extra buttons.

Opted not to include a Field of View slider. While this is possible, the way a particle system is built, caused the size of the particles to scale strangely, and there did not seem to be a great benefit in offering the feature. If there is interest in this, I can add the code to enable this easily.