Removes unnecessary code. Refactors some bits and fixes others.
Adds ability to render nighttime maps. This is done through the
`-light N` command line argument. N is a numeric value in the
range 0 to 15. Where 0 is complete darkness and 15 is full
bright daylight. When rendering light levels <15, any blocks
which emit light themselves, will be better visible. This
includes torches, lava, redstone, etc. The light emissions will
effect neighbouring blocks, just like they would in Minecraft
itself.