Clean up game id urls

[WandererXII]

Mentioned here: #1006

Currently we show either Game view or Analysis board view based on game state and Player/Spectator role. This is kinda ugly. There are two types of game ids - 8 characters long, 12 characters long (last 4 characters encode player). It's like this:

URL	Player	Spectator
/abcdefgh - during game	Game (changed to long id)	Game
/abcdefgh - after game	Analysis board	Analysis board
/abcdefgh1234 - during game	Game	Game (redirect to short id)
/abcdefgh1234 - after game	Game	Analysis board (redirect to short id)

I propose, we stop using full id, do not change views based on game state, and do not show completely different views for the same url to different people:

URL	Player	Spectator
/abcdefgh	Game	Game
/abcdefgh/analysis - during game	Game (redirect)	Game (redirect)
/abcdefgh/analysis - after game	Analysis board	Analysis board

Keep old urls working with redirects.

[WandererXII]

One could even argue that Game view is not necessary after game finishes... Keeping only one url, might be nicer... (Only after chats are merged and rematch button is added to analysis board)

URL	Player	Spectator
/abcdefgh - during game	Game	Game
/abcdefgh - after game	Analysis board	Analysis board