quad: delete unused files (13 files?!?!)

quad/src/quad_app/PID.c

quad/src/quad_app/README.txt

quad/src/quad_app/control_algorithm.h

quad/src/quad_app/controllers.c

quad/src/quad_app/controllers.h

quad/src/quad_app/gam.h

quad/src/quad_app/new_PID.h

quad/src/quad_app/new_log_data.c

quad/src/quad_app/new_log_data.h

quad/src/quad_app/old_log_data.h

quad/src/quad_app/packet_processing.c

quad/src/quad_app/packet_processing.h

quad/src/quad_app/quad_app.c

quad/src/quad_app/quadposition.h

quad/src/quad_app/sensor.h

quad/src/quad_app/sensor_processing.c

quad/src/quad_app/update_gui.c

quad/src/quad_app/update_gui.h