MegaPov's glow function

The glow function is a new type of atmospheric effects lately introduced to megapov 0.6. originally developed by Marcos Fajardo, later included in Megapov Plus and further developed by Chris Huff.

The syntax is the following

glow {
  type 0 | 1 | 2 | 3
  location LOCATION
  size FLOAT_SIZE
  radius FLOAT_RADIUS
  fade_power FLOAT_POWER
  color COLOR
  WARPS
  TRANSFORMS
}

type 2 and 3 are not yet completely implemented and therefore i did not include them here.

The file size of the tables is about 50-70k.