Bedrock Crafter

* Fixed advancements (you should no longer get most of them at once when unlocking just one; they'll work properly)

* Changed the "It's Not Impossible!" advancement a little

---- It will give 640 experience points when it's achieved, and it's hidden until you achieve its parent ("Impossible?")

* Attempted improving Bedrock Pickaxe mining again

---- Instead of checking if you're in an End biome, it just checks to see if the block at the bottom of the world below your position isn't bedrock. This means trying to get back bedrock from a large platform you've built at the bottom of the world may be annoying, but I figured it was better than either nothing or potential weirdness/inconsistencies :p

---- Technically, it's also supposed to check to make sure the block you're trying to "mine" isn't in the same position as the one it checks for the bottom of the world, but this doesn't seem to cancel the mining when it's a different, bedrock-like block so idk. Be careful if you've used polished bedrock etc. by the void!