Changelog
Fixes:
1. Each time the game score updates it runs a check where it encrypts the current code and hash compare it to the variable lastcode. At the end, if this turns out true, then it uploads the score (based on difficulty) and then encrypts that score and saves it as lastcode. It would now take a serios effort and nobody in their right mind would undertake to find the key to the encryptor to hack the gamescore.
2. Yetis now properly despawn.
3. Yetis will NOT despawn if HELL is selected, making this difficulty progressively harder.
4. Small spawn location tweaks.