UserListView and UserItem were added as the backbone of the user-list,
and the (currently unused) Caya message CAYA_SEND_INVITE was established
for inviting users to rooms.
Some menus were reworked (e.g., pop-ups of the RosterListView) or
generally tweaked to be more sensical or consistent.
Now all instances of sending messages (bar status changes) to a
conversation's CayaRenderView only happen when attached to the window.
Messages sent by user appear after the protocol confirms it's been sent
(IM_MESSAGE_SENT), rather than appearing right after the user sends it
to the protocol (IM_SEND_MESSAGE).
Logs are now re-enabled (since they can safely be appended under any
circumstance).
All chats now stay in a single window, which removes and switches its
current ConversationView with the appropriate one using
Conversation::GetView().
This is a stepping-stone to merging the ChatWindow into the MainWindow.
Jaidyn Ann