Some refactoring + fixes

The biggest fix is that the reset function is fixed. The score is reset as it ought to be, and the timer is fixed so that it properly resets.

A previous commit deliberately made the score persistent, but no rationale was given. From a game design perspective, the score should be reset. Keeping the score is like starting a new game on an RPG at level 58.

New bugs: resetting mid-run and then finishing causes the timer to not be stopped. The fact that this bug happens is a good thing, actually. As the code gets cleaned up, and the state is more properly encapsulated, the cause should eventually be found and fixed properly. The fact that there is a bug proves that the state is not mutated cleanly, and now that we know something is definitely wrong with the way state is handled, giving it a proper fix will improve the overall code quality