rail color

[AG]

craij was asking how to set rail color from within the game but i couldn't figure out which cvar did what.

• color: rail trail
• color1: rail core
• color2: rail spiral

i don't want the goofy spiral rail effect so i set cg_oldRail to 1 -- to change the color of the rail core, set color1 to one of the colors b/g/c/r/m/y/w numbered 1-7 respectively.