Copter: MAV_CMD_CONDITION_YAW accepted outside missions

Hello,

I have added the **MAV\_CMD\_CONDITION\_YAW** management in **COMMAND\_LONG** message. Now it will be possible to change yaw during a mission or guided mode without using a mission item.

I moved the code of "*do\_yaw*" function from **`commands_logic.pde`** into a dedicated function "*set\_auto\_yaw\_look\_at\_heading*" in **`control_auto.pde`**. This function is now called by both **`commands_logic.pde`** (for mission items) and **`GCS_Mavlink.pde`** (for command long message).

Best regards,

MousS'