Do not instantiate ServerComputer instances in the peripheral provider

Instead we create a ComputerProxy, which delegates methods to the
ServerComputer or TileComputerBase, depending on which one exists.

src/main/java/dan200/computercraft/shared/computer/blocks/ComputerPeripheral.java

@@ -10,7 +10,6 @@ import dan200.computercraft.api.lua.ILuaContext;
 import dan200.computercraft.api.lua.LuaException;
 import dan200.computercraft.api.peripheral.IComputerAccess;
 import dan200.computercraft.api.peripheral.IPeripheral;
-import dan200.computercraft.shared.computer.core.ServerComputer;
 
 import javax.annotation.Nonnull;
 
@@ -18,9 +17,9 @@ public class ComputerPeripheral
     implements IPeripheral
 {
     private final String m_type;
-    private final ServerComputer m_computer;
+    private final ComputerProxy m_computer;
 
-    public ComputerPeripheral( String type, ServerComputer computer )
+    public ComputerPeripheral( String type, ComputerProxy computer )
     {
         m_type = type;
         m_computer = computer;

src/main/java/dan200/computercraft/shared/computer/blocks/ComputerProxy.java

@@ -0,0 +1,87 @@
+package dan200.computercraft.shared.computer.blocks;
+
+import dan200.computercraft.shared.computer.core.ServerComputer;
+
+/**
+ * A proxy object for computer objects, delegating to {@link ServerComputer} or {@link TileComputer} where appropriate.
+ */
+public abstract class ComputerProxy
+{
+    protected abstract TileComputerBase getTile();
+
+    public void turnOn()
+    {
+        TileComputerBase tile = getTile();
+        ServerComputer computer = tile.getServerComputer();
+        if( computer == null )
+        {
+            tile.m_startOn = true;
+        }
+        else
+        {
+            computer.turnOn();
+        }
+    }
+
+    public void shutdown()
+    {
+        TileComputerBase tile = getTile();
+        ServerComputer computer = tile.getServerComputer();
+        if( computer == null )
+        {
+            tile.m_startOn = false;
+        }
+        else
+        {
+            computer.shutdown();
+        }
+    }
+
+    public void reboot()
+    {
+        TileComputerBase tile = getTile();
+        ServerComputer computer = tile.getServerComputer();
+        if( computer == null )
+        {
+            tile.m_startOn = true;
+        }
+        else
+        {
+            computer.reboot();
+        }
+    }
+
+    public int assignID()
+    {
+        TileComputerBase tile = getTile();
+        ServerComputer computer = tile.getServerComputer();
+        if( computer == null )
+        {
+            return tile.m_computerID;
+        }
+        else
+        {
+            return computer.getID();
+        }
+    }
+
+    public boolean isOn()
+    {
+        ServerComputer computer = getTile().getServerComputer();
+        return computer != null && computer.isOn();
+    }
+
+    public String getLabel()
+    {
+        TileComputerBase tile = getTile();
+        ServerComputer computer = tile.getServerComputer();
+        if( computer == null )
+        {
+            return tile.m_label;
+        }
+        else
+        {
+            return computer.getLabel();
+        }
+    }
+}

src/main/java/dan200/computercraft/shared/computer/blocks/TileComputer.java

@@ -19,14 +19,14 @@ import net.minecraft.util.EnumFacing;
 import net.minecraft.util.NonNullList;
 
 import javax.annotation.Nonnull;
-import java.util.List;
 
 public class TileComputer extends TileComputerBase
 {
     // Statics
 
     // Members
-
+    private ComputerProxy m_proxy;
+    
     public TileComputer()
     {
     }
@@ -48,6 +48,23 @@ public class TileComputer extends TileComputerBase
         return computer;
     }
 
+    @Override
+    public ComputerProxy createProxy()
+    {
+        if( m_proxy == null )
+        {
+            m_proxy = new ComputerProxy()
+            {
+                @Override
+                protected TileComputerBase getTile()
+                {
+                    return TileComputer.this;
+                }
+            };
+        }
+        return m_proxy;
+    }
+
     @Override
     public void getDroppedItems( @Nonnull NonNullList<ItemStack> drops, boolean creative )
     {

src/main/java/dan200/computercraft/shared/computer/blocks/TileComputerBase.java

@@ -386,6 +386,8 @@ public abstract class TileComputerBase extends TileGeneric
 
     protected abstract ServerComputer createComputer( int instanceID, int id );
 
+    public abstract ComputerProxy createProxy();
+
     // ITerminalTile
 
     @Override