Add orbit_smoothness option, fix bug, and add animation example

[Plonq]

• Adds orbit_smoothness option so you can change how smooth the orbiting motion is
• Fixes bug that meant you could only programmatically update the camera's position if it was the 'active' camera. This meant that a) you had to click once before it would work, and b) you could only control one camera at a time.
• Add animate example which demos how to animate the camera's motion
• Minor renaming and comment fixing