Flatworld Dimension

Adds a simple flatworld dimension.

World settings:
  Y Level | Block
  
      -64 | Bedrock
-63 to -1 | Dirt
        0 | Grass block

Meant for admin use-create the portal and get the igniter in creative mode.
Works great with essentials for setting warps/homes.

Portal is made with bedrock and lit with a "Flatworld Portal Activator".

This was created for personal use but I'm sharing in case others need the same functionality for their forge server.