Refactoring how talents target

[yufra]

I had a brief discussion with DG about refactoring how talents use target, and changing how both AI, preUseTalent and the MapMenu dialogs worked with that targeting. I have completed an initial revision and it does appear to work as desired, but I am not convinced it a good way to go about it. I would appreciate input from other code monkeys. My brain has been pretty zonked while coding this, so don't be surprised if it is ugly and feel free to suggest better ways to do it. Thanks!