Create the ability to call up an npc dialog within an event

Submitted for review, critique, and if all is well, inclusion in the engine.

It still has 3 flaws, but otherwise works:
-the labels are a little funky
-It won't switch to from talker to vendor (IMHO, that shouldn't be necessary functionality, as we just need regular dialog, and it might be easily fixed once hean01's changes come down)
-you still have to define the npc as an [npc] SOMEWHERE in the map, even if you can't see them, preferably placed in some horrible corner of the map like -1000,-1000,1,1 so that nobody ever has to see them.