MacOs - Full support

[adrienrn]

Dotfiles directory discovery does not work,

$BASH_SOURCE returns -bash on login via Terminal.app and readlink -f is only GNU.

http://stackoverflow.com/questions/5756524/how-to-get-absolute-path-name-of-shell-script-on-macos

Solution for now: manually set the $DOTFILES_DIR or put dotfiles in ~/.dotfiles

[adrienrn]

Colors for ls, diff, etc.. dicolors does not work.