Difficulty update

First time using the actual merge request feature, I might have done something incorrectly.

Just a quick update to difficulties that I've decided should be there regardless of what form the start zone rescaling takes. The loss of stats on higher difficulties is very arbitrary and removing it helps simplify the ruleset which is good for balancing and player understanding. Instakill immunity protects against a number of things that force turn skips, and absolutely nobody finds dying to Stone Touch fun or interesting. Its just random and stupid.

Forced start zones allowing rares is almost certainly going to be a problem no matter how well scaling is addressed.