Start adding Leap Motion support
Initialize a leap controller
Add a simple listener; the tap gesture pauses and resumes calculations
The circle gesture runs the simulation forward and backward

Clockwise integrates the affine parameter backward; while
counterclockwise integrates the affine parameter forward.
Drop all the gestures in the gesture list except the last one
Use single finger(s) to perform rotation and zoom
Actually implement rotation
Actually implement zoom
Remove the tap gesture to improve usability
Reimplement gestures control
Merge branch 'develop' into master