Add timer

[JayPi4c]

I'd like to have a timer implemented which allows to provide a little local offline leaderboard. Comparable to gnome mines or mahjong.

[Til7701]

Thanks for the issue. I am not huge fan of timers in those kinds of games, but I am open to adding a timer that can be hidden/disabled to Puzzled.

There would have to be a leaderboard for each puzzle I guess, since they are so different.

If you would like to implement this, here are some pointers:

• Currently, the dynamic metadata of puzzles is saved using the PuzzleMeta struct. So this would need methods to add a time for a puzzle and query the leaderboard. Maybe save the best 5 or 10 times for each puzzle.
• Those new methods should be used in the PuzzleModel struct to allow access to that data for the views.
• The puzzle page needs a timer that counts up the moment you open the puzzle or move the fist tile. The is a solved signal which should already be used to update the solved state and hints used. There you would need to add the insertion of the time in the leaderboard using the PuzzleModel.
• A fist implementation does not necessarily need all features like hiding/disabling the timer or caching to improve performance.