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).
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.
Now all active conversations will be listed in the main window, in a
ConversationListView. Clicking one of the items will open its
conversation window as you'd expect, etc.
Jaidyn Ann