Handles case where the app receives only a subset of the SMS messages
into which a larger game-level message has been broken. Now when it
restarts and the remaining parts come in the whole can be reassembled.
Trying to separate what's game-specific from what can be app/device
specific (i.e. with a long lifespan, and available when a game isn't
open.)
Android will be broken after this commit and fixed after the next