Revert "Block: Get rid of state bitmasks"

This reverts commit b7b05e729e.

Apparently this was premature, because we still need these things to deal with default state remapping.

src/pocketmine/block/Liquid.php

@@ -77,6 +77,10 @@ abstract class Liquid extends Transparent{
 		$this->still = $id === $this->idInfo->getSecondId();
 	}
 
+	public function getStateBitmask() : int{
+		return 0b1111;
+	}
+
 	public function hasEntityCollision() : bool{
 		return true;
 	}