Bump version to 0.2.9
Hide inside client monad the details of connecting to server

Previously they were defined, using liftIO, outside.
Do client saves in the background
Move thread accounting to a separate file
Parameterize waitForChildren
Make the client wait until the save thread ends
Let client save the game even on crash or C-c
Do server saves in the background
Factor out the common save code of client and server
Don't display the save command in the main menu
Get rid of SaveExitA
Make a backup save each n clips, as advertised, not each n turns
When the server crashes, make it wait for clients to save
Factor out the common game restore code of client and server
In case of corrupted client savefiles, delete server savefile

So that a new game can be started easily