Lots of tidying up done today, making the game look a bit better. Katia has started working on new snake images to fit the new board size, but they're not done yet.
I've added a new invulnerability powerup, which lets you slither through yourself, other snakes, or bones - but if you're still crossing them when you leave invulnerability, you die. You can still eat friendly powerups in the meantime. You flash faster and faster as your time runs out.