Mov notification stuff to separate files.

* weechat-sauron.el: for the sauron stuff
* weechat-notifications.el: for the notifications.el stuff

Reduce the size of weechat.el!

Signed-off-by: Rüdiger Sonderfeld <ruediger@c-plusplus.de>
Remove trailing x. (M)

Signed-off-by: Moritz Ulrich <moritz@tarn-vedra.de>
Change notification handler var to `weechat-notification-handler-functions'.

Signed-off-by: Moritz Ulrich <moritz@tarn-vedra.de>
README: documentation about the notification stuff.

Signed-off-by: Rüdiger Sonderfeld <ruediger@c-plusplus.de>
Move defvars past defcustoms. (M)

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