When no accounts are active, all items in the Menubar->Chat menu are
disabled, and some other menu items related to starting/managing chats
are disabled in other views.
One new message was added to the API― IM_PROTOCOL_READY, which tells
Caya that a given protocol has logged in and is ready to receive
messages (rather than just sending).
This is currently done in XMPP after the roster is loaded, which be a
process that stalls the protocol for a few seconds. IM_PROTOCOL_READY
should only be sent after those initial, potentially time-heavy
operations.