Most of the switch statement in create_part is gone. There's a few others that I will get rid of in future commits. There will also be a CreateAllowed function, and a ChangeType. ChangeType will handle stuff that is duplicated in both create_part and part_change_type. Considering making a Destroy function instead of ChangeType, though.
Later on, Lua events will be made for all 3
Credit to jacksonmj for the original design of all of this, I copied it into my mod years ago
