Friendly monster AI

Just implemented an effective friendly monster AI in about 2 hours - much easier than anticipated. I just need to allow the player to order his minions around, and have them not disturb the player whilst moving.

Its testament to Leon Marrick's 4GAI code, as well as the future proofing I did previously to the monster spell code.

Unfortunately, I now have to balance the player summoning unlimited monsters, as well.

For those of you waiting on the next Unangband release, a bug on the Berlios site is preventing me from releasing. Consequently, I've gone on to implement lots of extra features instead, including the AI code I've just mentioned.