Check if odomentry is calculated correctly in the simulation while decelerating

[marian42]

cc @harunteper

[Nils-Jung]

At the moment, the VESC simulator calculates odometry purely with messages sent to "/commands/motor/speed". Therefore, if the car is driving and is then sent a command to stop (setting speed to 0), the vesc sim thinks that the car has stopped instantly while the actual car is still rolling. By the way, the real vesc package calculates odometry with the real motor speed it gets from the motor controller. That motor speed is directly linked to the speed of the tires; therefore I think it would be a good idea and not a hack to get our simulated odometry from the speed of the (simulated) tires.