InertialNav: added get_velocity_xy
Copter: TOY mode updates
Copter: remove unused Toy param
Copter: remove unused get_acro_yaw
Copter: CH7 SaveWP fix corner case

If the user is on the ground and flips CH7, do nothing instead of recording a bad takeoff altitude. Do another check to avoid a land right after a takeoff.
AutoTest: copter ch7 option to SaveWP
AutoTest: wait 1sec when saving wp
AutoTest: remove unnecessary wait from SaveWP test