View nonactive turn

I have added capability to view a game where you cannot currently play a turn.

I have also added redirects of convenience when logging in, and when selecting a game from the overview screen.

Pass attacks now work.

Known bugs:
- only the game with the highest game_id (i.e., the most recent) can be activated
- the redirect from the overview screen does not correctly redirect to the choose_swing page when that is required
- end-of-turn logic does not yet force swing select for the round loser