Since ConversationViews were manually removed/added previously, now
that a BCardLayout is used, the visibility-detection/some actions
change (e.g., using BView::Show instead of BView::AttachedToWindow).
CreateAccountMenu() is used to populate a BMenu with items corresponding
to the map of accounts provided to it― but when an account is disabled
or enabled, it can't update automatically.
A dedicated class, fAccountsMenu, now replaces it― it'll automatically
repopulate the list whenever the active accounts update.
When a new message is posted (or the user is messaged), the room's item
in the roomlist is now highlighted, like Vision.
Chat also auto-scrolls when new messages are posted.
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.
Jaidyn Ann
plfiorini