Raft Mod Loader v4.0-pre

Changelog for RaftModLoader 4.0-PRE

• Added class RAPI which contains methods for the main Raft API and other stuff.
• Added class ModItem which allows you to add new items/blocks to the game.
• Added a lot of code for the serverlist that isn't yet active.
• Updated Harmony to 1.20.
• Fixed a messagebox error popup when closing the mod loader while a mod hasn't been properly unloaded.