Superflat Progression

Initial release:

• New mob: pixies
• New crafting station: Scriptorium. Create magic scrolls with parchment and pixie dust to change the weather and summon mobs.
• New crafting station: Pulverizer. Convert stone into gravel and sand, convert diamond tools into diamond shards, convert magma blocks into lava
• Made charcoal and cobblestone available in structureless superflat through setting logs on fire, using a water bottle on a magma block.
• Made End portal frame generator block which create an End portal frame when activated.
• Made the Nether and the End superflat when the world preset is used.