NPC Targetting improvements

This addon is a buff for NPC's.
It improves the way NPC's locate and keep track of the player when they can't see or otherwise detect him/her.

Tracking is less random, has a limited amount of error, and is more consistent from turn to turn.

The tooltip for NPC's has been updated to give stealthed/invisible players a hint about which enemies have successfully detected them.

This addon is compatible with ToME 1.0.5, commit a801604d1610f49560862d15dfaecd03fda8ab40

It includes changes to:

engine.interface.ActorAI.lua
mod.class.NPC.lua

tome-NPCTarget.teaa

tome-NPCTarget.teaa