Allow outpost to "WAVE OFF" the supply ship

[hackerb9]

The original PET version of OUTPOST allowed one to intentionally destroy the supply ship, which gives 5 points (ET(5)), which is more points than you get for even destroying the heaviest battleships. Blowing it up doesn't make any sense, but it would be nice if there was a new option, W, for WAVE OFF that would serve the same purpose strategically. This would require a new routine at line 6600 similar to the "Enemy Destroyed" routine in 6500.