Implement invisible bedrock to fix placement issues

I don't know why this wasn't done a long time ago, but here it is.

src/pocketmine/block/BlockFactory.php

@@ -171,7 +171,7 @@ class BlockFactory{
 		self::registerBlock(new Cake());
 		//TODO: REPEATER_BLOCK
 		//TODO: POWERED_REPEATER
-		//TODO: INVISIBLEBEDROCK
+		self::registerBlock(new InvisibleBedrock());
 		self::registerBlock(new Trapdoor());
 		//TODO: MONSTER_EGG
 		self::registerBlock(new StoneBricks());

src/pocketmine/block/InvisibleBedrock.php

@@ -0,0 +1,51 @@
+<?php
+
+/*
+ *
+ *  ____            _        _   __  __ _                  __  __ ____
+ * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \
+ * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
+ * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/
+ * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_|
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * @author PocketMine Team
+ * @link http://www.pocketmine.net/
+ *
+ *
+*/
+
+declare(strict_types=1);
+
+namespace pocketmine\block;
+
+use pocketmine\item\Item;
+
+class InvisibleBedrock extends Transparent{
+
+	protected $id = self::INVISIBLE_BEDROCK;
+
+	public function __construct(){
+
+	}
+
+	public function getName() : string{
+		return "Invisible Bedrock";
+	}
+
+	public function getHardness() : float{
+		return -1;
+	}
+
+	public function getBlastResistance() : float{
+		return 18000000;
+	}
+
+	public function isBreakable(Item $item) : bool{
+		return false;
+	}
+}