Remove the 'cheated' flag in Range's game_ui, which was stickily

Remove the 'cheated' flag in Range's game_ui, which was stickily
remembering whether the player had ever used the hint or solve
functions, even if they then pressed undo (and even if they saved and
restored).

As far as Solve+Undo is concerned, this just brings Range into line
with common practice in the rest of my puzzles. On the other hand,
Range is the first time there's been a 'hint' function to consider in
this question, so here's a policy decision: the victory flash is not a
congratulation for a puzzle solved unaided, it's a confirmation that
you really have reached a correct solution and haven't made any
mistakes. So the only reason to omit the victory flash is if you've
used the Solve operation to go straight to a guaranteed-correct
solution _in a single move_; if you're using the hint button, there's
still scope for you to make mistakes in all your non-hint moves, so
the victory flash is still a useful indicator that you didn't.

[originally from svn r9306]