Add chopper waypoints
Cause chopper to lift off when squad leaves staging area
Configure chopper to ignore and be ignored by enemies
Make chopper fly off into distance and disappear

* Players start in chopper in the air, and descend vertically
  to mission staging area. Trusting the AI to make a full flight
  into the chosen staging area is probably asking a bit too much.
* Add four other playable units.
Add mines and satchel charges to chopper
Don't name squad members
Make chopper wait for squad to leave staging area
Change Ifrit GMG to HMG