msg: Use the correctly data types on vehicle_command

Lets save a few bytes using the right data types.

msg/vehicle_command.msg

@@ -98,9 +98,9 @@ float32 param4			# Parameter 4, as defined by MAVLink uint32 VEHICLE_CMD enum.
 float64 param5			# Parameter 5, as defined by MAVLink uint32 VEHICLE_CMD enum.
 float64 param6			# Parameter 6, as defined by MAVLink uint32 VEHICLE_CMD enum.
 float32 param7			# Parameter 7, as defined by MAVLink uint32 VEHICLE_CMD enum.
-uint32 command			# Command ID, as defined MAVLink by uint32 VEHICLE_CMD enum.
-uint32 target_system		# System which should execute the command
-uint32 target_component		# Component which should execute the command, 0 for all components
-uint32 source_system		# System sending the command
-uint32 source_component		# Component sending the command
+uint16 command			# Command ID, as defined MAVLink by uint32 VEHICLE_CMD enum.
+uint8 target_system		# System which should execute the command
+uint8 target_component		# Component which should execute the command, 0 for all components
+uint8 source_system		# System sending the command
+uint8 source_component		# Component sending the command
 uint8 confirmation		# 0: First transmission of this command. 1-255: Confirmation transmissions (e.g. for kill command)

src/modules/events/send_event.cpp

@@ -257,8 +257,8 @@ int SendEvent::custom_command(int argc, char *argv[])
 		}
 
 		vehicle_command_s cmd = {};
-		cmd.target_system = -1;
-		cmd.target_component = -1;
+		cmd.target_system = 0;
+		cmd.target_component = 0;
 
 		cmd.command = vehicle_command_s::VEHICLE_CMD_PREFLIGHT_CALIBRATION;
 		cmd.param1 = (gyro_calib || calib_all) ? vehicle_command_s::PREFLIGHT_CALIBRATION_TEMPERATURE_CALIBRATION : NAN;