ShulkerBox Dupe Prevention - Fixes #488

This ensures that Shulker Boxes can never drop their contents twice, and
that the inventory is cleared incase it some how also got saved to the world.

Spigot-Server-Patches/0201-ShulkerBox-Dupe-Prevention.patch

@@ -0,0 +1,23 @@
+From d820d766f014a27f41905e911a148ac7024befaa Mon Sep 17 00:00:00 2001
+From: Aikar <aikar@aikar.co>
+Date: Mon, 2 Jan 2017 16:32:56 -0500
+Subject: [PATCH] ShulkerBox Dupe Prevention
+
+This ensures that Shulker Boxes can never drop their contents twice, and
+that the inventory is cleared incase it some how also got saved to the world.
+
+diff --git a/src/main/java/net/minecraft/server/BlockShulkerBox.java b/src/main/java/net/minecraft/server/BlockShulkerBox.java
+index fcb1a6c66..12fb81635 100644
+--- a/src/main/java/net/minecraft/server/BlockShulkerBox.java
++++ b/src/main/java/net/minecraft/server/BlockShulkerBox.java
+@@ -109,6 +109,7 @@ public class BlockShulkerBox extends BlockTileEntity {
+                 }
+ 
+                 a(world, blockposition, itemstack);
++                tileentityshulkerbox.clear(); // Paper - This was intended to be called in Vanilla (is checked in the if statement above if has been called) - Fixes dupe issues
+             }
+ 
+             world.updateAdjacentComparators(blockposition, iblockdata.getBlock());
+-- 
+2.11.0
+