Removed entanglement between chunks and providers. WARNING: BREAKING API CHANGES.

- All entity and tile constructors now require a \pocketmine\level\Level instead of a \pocketmine\level\format\Chunk.
- Chunk->getProvider() and Chunk->setProvider() have been removed.
- Chunk::__construct() has had the $provider parameter removed.
- Chunk->unload() has had the unused $save parameter removed.
- ChunkEvents now take a Level parameter instead of going through the Chunk

API bump to 3.0.0-ALPHA4

src/pocketmine/level/format/io/region/Anvil.php

@@ -134,7 +134,6 @@ class Anvil extends McRegion{
 			}
 
 			$result = new Chunk(
-				$this,
 				$chunk["xPos"],
 				$chunk["zPos"],
 				$subChunks,