mecanum: separate velocity control

msg/CMakeLists.txt

@@ -131,6 +131,7 @@ set(msg_files
 	ManualControlSwitches.msg
 	MavlinkLog.msg
 	MavlinkTunnel.msg
+	MecanumVelocitySetpoint.msg
 	MessageFormatRequest.msg
 	MessageFormatResponse.msg
 	Mission.msg

msg/MecanumVelocitySetpoint.msg

@@ -0,0 +1,5 @@
+uint64 timestamp # time since system start (microseconds)
+
+float32 speed # [m/s] [-inf, inf] Speed setpoint
+float32 bearing         # [rad] [-pi, pi] from North.
+float32 yaw 	        # [rad] [-pi, pi] (Optional, defaults to current vehicle yaw) Vehicle yaw setpoint in NED frame