Minor adjustments for Icy Slimes and mod files.

Today, I pushed a small update:

Icy slimes no longer spread snow. This was requested by a player and supported with reasons. Icy slimes are spreading snow too much and spreading the snow biome rapidly as a result. To prevent this, icy slimes no longer spread snow. They will still spread ice when in water.

Also, changes were made to the game folder structure. /docs and /mods_disabled folders have been removed. Documentation should be available in an easy to consume fashion for players and developers. However, it makes more sense to maintain a more accessible version on the website. When documentation is more final, documents can be dropped back into a /doc folder within the game files for modders/users/etc.