Very rudimentary particle system support

Also highly wasteful at the moment since it's allocating huge piles of
memory statically. I'll trim it down and have it dynamically allocate
once I've got the functionality working.

So far there are three types of particle system: points, lines, and
lightning. Points are the same as stock Q2 particles. As a demonstration
and/or testbed of the other two types, I tinkered up new effects for the
EF_TELEPORTER and EF_BLASTER effect flags.
Minor particle ugliness fix.
First pass at the lightning gun code.

Haven't tried this in multiplayer, but it should be fun. You want to be
outside the water and shooting at someone in it. Mostly just a way to play
around with PARTICLE_TYPE_LIGHTNING systems.
sv_alternatespawns replaces the hyperblaster with the lightning gun in all maps. This is extensible so we can override a whole set of spawns in one lookup array.
custom pakfile

This contains the models and stuff for the lightning gun.
lightning gun behavior changes

now it arcs everywhere, but arcs farther and does triple damage in
water.
Converting particles to systems

Converted all loose particles to particlesystems.
No more legacy particles.

Also a minor bugfix in the line width calculations.
Merge branch 'lightning_gun' into particles
Fix lightning gun particles.

(adjusted all the numbers on them to match the fixed particle system
code.)
Sprite particles! \o/

Particle systems can now specify the name of a texture to use for
rendering them. Also added scale parameters.
billboarded sprite particles.
Merge branch 'particles'