Positronic brains and friends.

Hawk said to just issue this request despite the additional files committed to it. The only files I actually want to merge with BEF are:

code/game/machinery/computer/ai_core.dm
code/game/mecha/mecha.dm
code/game/objects/items/robot/robot_parts.dm
code/modules/mob/living/carbon/brain/say.dm
/icons/obj/assemblies.dmi

There is a bug with destroying a mech containing a positronic brain that I haven't resolved yet, and the timer doesn't work. You can't get these in-game yet without adminhax.