At some point, someone did a find and replace over this file, and completely screwed up the signal for Knockdown().
This caused components that relied on it, like the Knockoff component, to work way less often.
This PR fixes that.
It also goes through and cleans up the Knockoff component. More consistent style guide stuff, minor improvements, better documentation.
It also unit tests it.
Loosely adapted from /vg/. This is an entity component system for adding behaviours to datums when inheritance doesn't quite cut it. By using signals and events instead of direct inheritance, you can inject behaviours without hacky overloads. It requires a different method of thinking, but is not hard to use correctly. If a behaviour can have application across more than one thing. Make it generic, make it a component. Atom/mob/obj event? Give it a signal, and forward it's arguments with a SendSignal() call. Now every component that want's to can also know about this happening.
