SITL → AP_Motors Relation

File in libraries/SITL	Includes file in libraries/AP_Motors
SIM_Frame.cpp	AP_Motors.h
SIM_Motor.cpp	AP_Motors.h
SIM_Multicopter.cpp	AP_Motors.h
SIM_SingleCopter.h	AP_Motors.h
SIM_Submarine.cpp	AP_Motors.h