Save items properly on several places, added NBT::getItemHelper() and NBT::putItemHelper()

src/pocketmine/item/Item.php

@@ -1039,6 +1039,15 @@ class Item{
 
 		return $this;
 	}
+
+	public function getNamedTagEntry($name){
+		$tag = $this->getNamedTag();
+		if($tag !== null){
+			return isset($tag->{$name}) ? $tag->{$name} : null;
+		}
+
+		return null;
+	}
 	
 	public function getNamedTag(){
 		if(!$this->hasCompoundTag()){

src/pocketmine/item/Tool.php

@@ -24,6 +24,7 @@ namespace pocketmine\item;
 
 use pocketmine\block\Block;
 use pocketmine\entity\Entity;
+use pocketmine\nbt\tag\Byte;
 
 abstract class Tool extends Item{
 	const TIER_WOODEN = 1;
@@ -55,6 +56,10 @@ abstract class Tool extends Item{
 	 * @return bool
 	 */
 	public function useOn($object){
+		if($this->isUnbreakable()){
+			return true;
+		}
+
 		if($this->isHoe()){
 			if(($object instanceof Block) and ($object->getId() === self::GRASS or $object->getId() === self::DIRT)){
 				$this->meta++;
@@ -101,6 +106,11 @@ abstract class Tool extends Item{
 		return $levels[$type];
 	}
 
+	public function isUnbreakable(){
+		$tag = $this->getNamedTagEntry("Unbreakable");
+		return $tag instanceof Byte and $tag->getValue() > 0;
+	}
+
 	public function isPickaxe(){
 		return false;
 	}