Improved Color handling.

The Weechat color codes are a pretty shitty format and parsing them is
quite a pain...

http://www.weechat.org/files/doc/devel/weechat_dev.en.html#color_codes_in_strings
Signed-off-by: Rüdiger Sonderfeld <ruediger@c-plusplus.de>

Conflicts:
	weechat.el