Block: Clean up internal constructor inconsistencies

I don't dare look how big this commit is or how many bugs it introduced...

src/pocketmine/block/IronBars.php

@@ -27,16 +27,6 @@ use pocketmine\item\TieredTool;
 
 class IronBars extends Thin{
 
-	protected $id = self::IRON_BARS;
-
-	public function __construct(){
-
-	}
-
-	public function getName() : string{
-		return "Iron Bars";
-	}
-
 	public function getHardness() : float{
 		return 5;
 	}