Add hints

[amorris13]

Using IAPs

[amorris13]

Add a subscription for unlimited hints

[amorris13]

Initial implementation (without IAPs, so unlimited hints)

In Game UI:

• Hint action using lightbulb icon
• Hinted cards should be given a lighter blue border. Cards now have 4 states {unhinted, hinted} x {unselected, selected}.
• Pressing hint multiple times (up to 3) adds more cards to the hinted set.
• Hinted states cleared when triples are refreshed
• Section at the bottom should show whether a hint has been used (maybe show lightbulb icon?).

Help UI

• Explain hints

Game statistics

• Note whether a hint was used in the game and store that
• Don't upload score to leaderboards
• Change stats summary to include fastest/average/num finished both with and without hints
• In list of games, add * next to times for games with hints
• In histogram, use different shade of blue for games with hints (stacked bar chart style)

[amorris13]

Also TODO: Add warning when hint option is first selected per game that this will make this game ineligible for high scores.