changed cl_particles_quake mode to use size 1.5 for particles rather than size 1...

changed cl_particles_quake mode to use size 1.5 for particles rather than size 1.0, this makes them about as visible as in glquake
changed explosion sparks to not be affected by gravity and some other differences in how they are spawned
removed sparks on bullet/nail impact effects, made smoke bigger and a bit darker so it's not just small white puffs, it now looks rather nice, and more true to the original quake gunshot/spike/superspike effect

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@7026 d7cf8633-e32d-0410-b094-e92efae38249