FR: Allow particle_effects to be coloured via table entry, like weapons.

Currently weapons have entries like Laser Color: and Laser Color2:
It'd be great if a similar functionality could be given to particle_effects.tbl entries. allowing stuff like colour transitions and a random hue within a certain range. This could greatly reduce modder (and possible VRAM?) workload, as one would now only need to create monochrome particle effects and let FSO sort out the colouring.