[Bleeding] Implementation of inventory framework. Addresses BUKKIT-856

See the corresponding Bukkit commit for details.

Implementation details:
- Any packets that include an itemstack will send air stacks as null; maybe this will even eliminate the client crash that occurs if the client receives an air stack
- Better handling of null itemstacks in general (ie less converting them to air stacks)
- Inventory.setContents() can now take an array smaller than the inventory without error
- Player.updateInventory() should now correctly update the result slot in a crafting inventory

Some small credit goes to Afforess (initial implementation of openInventory() methods) and Drakia (initial implementation of InventoryOpenEvent and InventoryCloseEvent).

src/main/java/net/minecraft/server/Container.java

@@ -5,8 +5,13 @@ import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
 
-public abstract class Container {
+// CraftBukkit start
+import org.bukkit.craftbukkit.entity.CraftHumanEntity;
+import org.bukkit.craftbukkit.inventory.CraftInventory;
+import org.bukkit.inventory.InventoryView;
+// CraftBukkit end
 
+public abstract class Container {
     public List d = new ArrayList();
     public List e = new ArrayList();
     public int windowId = 0;
@@ -14,6 +19,18 @@ public abstract class Container {
     protected List listeners = new ArrayList();
     private Set b = new HashSet();
 
+    // CraftBukkit start
+    public boolean checkReachable = true;
+    public abstract InventoryView getBukkitView();
+    public void transferTo(Container other, CraftHumanEntity player) {
+        InventoryView source = this.getBukkitView(), destination = other.getBukkitView();
+        ((CraftInventory)source.getTopInventory()).getInventory().onClose(player);
+        ((CraftInventory)source.getBottomInventory()).getInventory().onClose(player);
+        ((CraftInventory)destination.getTopInventory()).getInventory().onOpen(player);
+        ((CraftInventory)destination.getBottomInventory()).getInventory().onOpen(player);
+    }
+    // CraftBukkit end
+
     public Container() {}
 
     protected void a(Slot slot) {