Restructure PaperSpigot as a new set of modules

Allows us much greater control over the Spigot portion of the code
and makes us more "proper"
Credit to @Dmck2b for originally passing the idea along a while back

CraftBukkit-Patches/0015-Handle-Null-Tile-Entities.patch

@@ -0,0 +1,25 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: md_5 <md_5@live.com.au>
+Date: Sun, 3 Feb 2013 09:20:19 +1100
+Subject: [PATCH] Handle Null Tile Entities
+
+
+diff --git a/src/main/java/net/minecraft/server/World.java b/src/main/java/net/minecraft/server/World.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/net/minecraft/server/World.java
++++ b/src/main/java/net/minecraft/server/World.java
+@@ -0,0 +0,0 @@ public abstract class World implements IBlockAccess {
+ 
+         while (iterator.hasNext()) {
+             TileEntity tileentity = (TileEntity) iterator.next();
++            // Spigot start
++            if (tileentity == null) {
++                getServer().getLogger().severe("Spigot has detected a null entity and has removed it, preventing a crash");
++                iterator.remove();
++                continue;
++            }
++            // Spigot end
+ 
+             if (!tileentity.r() && tileentity.o() && this.isLoaded(tileentity.x, tileentity.y, tileentity.z)) {
+                 try {
+--