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/block/SignPost.php

@@ -87,7 +87,7 @@ class SignPost extends Transparent{
 				$this->getLevel()->setBlock($block, new WallSign($this->meta), true);
 			}
 
-			Tile::createTile(Tile::SIGN, $this->getLevel()->getChunk($block->x >> 4, $block->z >> 4), $nbt);
+			Tile::createTile(Tile::SIGN, $this->getLevel(), $nbt);
 
 			return true;
 		}