rc_pilot controller is working in the full cooperative payload simulation

Finished porting code to be Simulink based. Working in Simulink, didn't add any new features though.

Working MATLAB-script based version of the simulation before switching to Simulink-based simulation.

Has preliminary wind model / drag model, LQR w/ integral action controller, reasonable planner, etc.

This version has the dynamics and methods prior to Matt's AIAA Aviation 2020 Paper. It works but may have had a small error in how the tether force was added to the vehicle dynamics.

It uses an LQR with integral action for control, and has a spring damper for tether forces. No aerodynamics are included. There may be a mistake in how the forces on the vehicle are calculated but near 0-attitude it shouldn't matter.