Auto-continue closes #3

Automatically continue after scoring when the player chooses a card to
play. Also happens to fix the heretofore elusive bug in which the dealer
plays None if the player drags all four cards onto the board.  Turns out
autoplay had no chance of catching that one!
Refactor settings to ini file

Auto-updater will keep file and in-memory representation synchronized.
Built backwards-compatible to existing references, though that may
change in the future still...