Robustify message display

Robustify message display

Adjust the behavior of the GameStateManager; it's not quite what it
should be, but it's less bad than what was there before.  Notably, Msg
objects now have the right .equals() behavior, not just .compareTo()

Improve CtFwSDisplayLocal and stay subscribed to game state changes
while not visible so we stay informed of messages.  Do not, however,
stay subscribed to service state messages, as there is no point.

We might lose messages all the same, but hopefully fewer and hopefully
without duplicates spamming everyone all the time.

While here, more correctly (I think?) use the Android lifecycle events.