Ports the emitter beams from /vg/

Credits to N3X15 for the original implementation over at /vg/ that I ~~stole~~*ported*

Emitters will now shoot continuous beams that can be concentrated by prisms. These deal damage every tick instead of shooting energy bullets.

Also included is an alternative implementation of an event system. While we do have our own (rather old) version, this one is faster, cleaner, simpler and overall just better.

One side effect of this is that setting up the singularity containment became significantly harder, since it's now impossible to walk through an emitter beam without taking heavy damage. I'm not sure that's really an issue, though.