Version 2!

It's much better now! I fixed:

• Fix castling
• Pieces that have been moved show a ghost piece
• Show how many pieces are attacking a square
• Calculate and show points
• Show defended icons bigger on mobile (put around your finger)
• Save on mobile (I think it's fixed after upgrading unity)
• King shouldn't be able to be defended
• Add simple random singleplayer
• Rotate the pieces for two player (run 180° transform on both the board and the pieces)