Challenge Mode

Hey everyone this update adds Challenge mode.

If you played the itch.io version, this is the same as Starter Decks.

Complete all the challenges, or try beat your high score on each challenge!

Added 3 new challenges:
- TURTLE
- AURAMAXXING
- Choose 10 for Gigachad

Bug fixes:
Fixed a problem where upgraded Back to Back didnt get the Gains from playing BACK TO BACK cards.
Fixed a problem where upgraded Kettlechin wouldn't return the card to your hand.
Fixed a problem where if you bought loose cards in the shop then removed a card afterwards, you couldn't click on the top row.
Fixed a problem where upgraded Hands-Free wasn't showing the upgraded draw amount.