Make notification handlers extendable

Signed-off-by: Moritz Ulrich <ulrich.moritz@googlemail.com>
indentation was fucked up. Fix it.

Signed-off-by: Moritz Ulrich <ulrich.moritz@googlemail.com>
Merge branch 'master' of git://github.com/the-kenny/weechat.el
Make `weechat-color-list' customizable.

Signed-off-by: Rüdiger Sonderfeld <ruediger@c-plusplus.de>