Added CraftingGrid and BigCraftingGrid, WIP stuff for crafting

moving whole stacks in & out of the crafting grid works now, splitting stacks is fucked up because the transaction system can't handle the same slot changing multiple times in one transaction

src/pocketmine/inventory/CraftingGrid.php

@@ -0,0 +1,53 @@
+<?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\inventory;
+
+use pocketmine\Player;
+
+class CraftingGrid extends BaseInventory{
+
+	public function __construct(Player $holder){
+		parent::__construct($holder);
+	}
+
+	public function getDefaultSize() : int{
+		return 4;
+	}
+
+	public function setSize(int $size){
+		throw new \BadMethodCallException("Cannot change the size of a crafting grid");
+	}
+
+	public function getName() : string{
+		return "Crafting";
+	}
+
+	public function sendSlot(int $index, $target){
+		//we can't send a slot of a client-sided inventory window
+	}
+
+	public function sendContents($target){
+		//we can't send the contents of a client-sided inventory window
+	}
+}