Plug world unload memory leak. Thanks @riking for identifying the issue.

CraftBukkit-Patches/0065-Plug-World-Unload-Memory-Leak.patch

@@ -0,0 +1,22 @@
+From abf88361148d182536726699838388895efda957 Mon Sep 17 00:00:00 2001
+From: md_5 <md_5@live.com.au>
+Date: Sat, 3 Aug 2013 19:02:59 +1000
+Subject: [PATCH] Plug World Unload Memory Leak
+
+
+diff --git a/src/main/java/net/minecraft/server/BlockRedstoneTorch.java b/src/main/java/net/minecraft/server/BlockRedstoneTorch.java
+index f176e66..d4f3c51 100644
+--- a/src/main/java/net/minecraft/server/BlockRedstoneTorch.java
++++ b/src/main/java/net/minecraft/server/BlockRedstoneTorch.java
+@@ -11,7 +11,7 @@ import org.bukkit.event.block.BlockRedstoneEvent; // CraftBukkit
+ public class BlockRedstoneTorch extends BlockTorch {
+ 
+     private boolean isOn;
+-    private static Map b = new HashMap();
++    private static Map b = new java.util.WeakHashMap(); // Spigot
+ 
+     private boolean a(World world, int i, int j, int k, boolean flag) {
+         if (!b.containsKey(world)) {
+-- 
+1.8.1.2
+