Particle laser works

Enemy ship is targeted automatically once moused over.

Bugs:

Enemy ship still gets aliased (nudge behaviour is  never reached)
Particles are not properly billboarded.
Particle beam will not disappear once enemy leaves screen.
Post Processing Effort - read below

Some progress made.

Still not sure if rendering the reticle in post-processing is smart due
to efficiency.

If you can implement a quick quad with texture, that would be best. If
unsure about alpha blending, I'll do it after. Could get away with
making a HUD class.