Added World to ChunkProviderEvent.ReplaceBiomeBlocks

Having a world variable allows modders using the ReplaceBiomeBlocks event to
a) use the world's random instead of creating their own, ensuring that worlds with the same seed are exactly the same,
b) check the dimension ID to make sure they are editing the generation of the right dimension if more than one dimension uses the same chunk provider (such as when another mod adds a new overworld type dimension, but you only want to change the standard overworld)