Resolve "Add LQR Control to Simulink"

controls/documentation/LQR_Design.md

controls/documentation/SimulinkModel.md

controls/model/Quadcopter_Model.slx

controls/model/Quadcopter_Model_R2015_A.mdl

controls/model/Quadcopter_Model_R2016_A.slx

controls/model/Quadcopter_Model_R2016_B.slx

controls/model/improved_lqr.m

controls/model/initial_lqr.m

controls/model/linearization.m

controls/model/lqr_err.m

controls/model/modelParameters.m

controls/model/repeated_opt.m

controls/model/rich_params.m

controls/model/run_once.m

controls/model/test_improved_lqr.m

controls/model/test_model.slx

controls/model/test_model_R2015A.mdl

controls/model/test_model_R2015Ax.slx

controls/model/weights_modern.mat

controls/model/weights_old_quad.mat