Added hooks for changing sky and clouds color

Added two new events: SkyColorEvent and CloudColorEvent.

Usage example: http://pastebin.com/wb6e6D0x
The way this is done, you're giving the sum of all reds, greens and blues and give the "divider" as a multiplier (which are the opposite of each other).

Might want to divide r, g and b with divider and leave out the multiplier parameter, instead add the distance variable to the event, so mods know how far they should search.