Implemented slime blocks

src/block/Slime.php

@@ -0,0 +1,44 @@
+<?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\entity\Entity;
+use pocketmine\entity\Living;
+
+final class Slime extends Transparent{
+
+	public function getFrictionFactor() : float{
+		return 0.8; //???
+	}
+
+	public function onEntityLand(Entity $entity) : ?float{
+		if($entity instanceof Living && $entity->isSneaking()){
+			return null;
+		}
+		$entity->resetFallDistance();
+		return -$entity->getMotion()->y;
+	}
+
+	//TODO: slime blocks should slow entities walking on them to about 0.4x original speed
+}