The conversation view now displays the protocol icon and room subject.
Messages for receiving room names (IM_ROOM_NAME) and subjects
(IM_ROOM_SUBJECT) were added, and support for the latter was given to
the XMPP add-on.
New message APIs were added, and several (room-related) im_what values were
moved into the 150s/160s.
UserItem::_TintColor() was moved to CayaUtils, because it can be used in
several different contexts.