Adds pAI Insertion Into Objects

Created by: Shadowmech88

This doesn't actually affect the game, this is purely the addition of a framework. I figure maybe now that it exists people might be inspired to do their own things with it.

This allows a pAI to be inserted into any /obj with its can_take_pai var set to TRUE. While inside an object, various hotkeys as well as mouse clicking can be used to trigger individual procs on the object corresponding to which hotkey was pressed. Altogether a pAI could manage 12 different functions of the object without even needing to use a menu.

Whenever an integrated pAI clicks an object that isn't its host object, on_integrated_pai_click() is called on the host object. By default, this simply calls attack_pai(), but if the proc has been overridden pAIs can still manually call attack_pai() on machinery by using Ctrl+click.