BlockType and ItemType API Completeness

Ensure API Completeness across the entire API

Input from others is welcome, as well as any criticism about missing API.
Don't know if this is a good idea but what if the silk touch enchantment has a block registry of blocks that can be harvested using that enchantment.
That way it avoids having specific methods in block that aren't directly related to the block type, but rather the enchantment instead.
All other methods on this interface describe properties of the block but `canHarvestWithSilk` describes how it behaves with a certain enchant on an item. Just a thought.