Adding RigitBodyThrust.m. This adds both a thrust and a moment due to aerodynamic drag from a propellor spinning, allowing a quadrotor to directly control its yaw.
Changes from Russ's code review.
Added addpath command in quadrotorDynamics.m unit test.
Merge pull request #361 from anirudhamajumdar/master

RigidBodyPropellor.m