AIUtils in prefix header

[David Smith]

	I'm considering adding a Cocoa.h style AIUtilities.h and including it  
in Adium's prefix header. I'd appreciate any feedback people have  
before I go ahead and do it :)

	Pros:
	AIUtilities methods will always show up in autocomplete, so we might  
actually remember additions we have
	Removes 800+ lines of imports
	Slightly less hassle
	*Very* slightly faster build

	Cons:
	Every time we change AIUtils we have to rebuild a ton of stuff

									David