Preserve LANG and LANGUAGE in the environment.

I believe vim needs LANG to bet set to xx_XX.UTF-8 to properly display utf8.
xterm should default to utf8 mode.
Comment and whitespace change.
Replace alias with setting in vimrc.
Use local variables.
Don't repeat yourself and use local variables.
Export DISPLAY only when it's actually used.
Simplify h() by making it a toggle and refactor.
Comment change.
Refactor.
Comment changes.
Comment changes.
Comment changes.
Rename color.sh to reflect that it is used as a lib.
Call color.sh by its new name.
Cache colors.
Change the layout of the prompt and intensive refactoring.
Improve readme.
Source fragments in alphabetical order.