VelocityVerletIntegrator

Basic velocity verlet method from http://en.wikipedia.org/wiki/Verlet_integration Uses the following format to extract positions and velocities: inputarray: y format: y = [x1, y1, vx1, xy1, x2, y2, vx2, vy2, ...] where the numbers indicate particles, x,y indicate position and vx,vy indicate velocities.