Generate spirograph curve into arrays `x` and `y` such that the i^th point * in 2D is represented by `(x[i],y[i])`. The generating function is given by: * \f{eqnarray*}{ * x &=& R\left[ (1-k) \cos (t) + l\cdot k\cdot\cos \left(\frac{1-k}{k}t\right) * \right]\\ * y &=& R\left[ (1-k) \sin (t) - l\cdot k\cdot\sin \left(\frac{1-k}{k}t\right) * \right] \f} * where * * \f$R\f$ is the scaling par