Optimal control example library expansion

[m427kirb]

Hi! I just wanted to add a new example to the optimal control library. The example : The quadcopter is an unmanned aerial vehicle with 4 propellors and in this case study, we seek to determine an optimal control policy for the 4 control inputs that must be adjusted over a specified time period to enable the quadcopter to closely follow given set points/trajectory while minimizing the difference between
the set point and actual position and propellor input.