Reduce some block updates

- Fix double updateOutput() call in TileComputerBase - I guess a
   merge/rebase gone wrong in the past.
 - Don't call updateBlock() when creating a server computer. This used
   to be needed when we sent the computer to the client, but this is no
   longer the case.
 - Don't call updateBlock() on TileMonitors when updating from the
   client. We don't need to do a redraw here, as this is all stored in
   the block state now.
 - Don't update the block when reading turtle upgrades. See #643 for
   some background here.

See #658

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

@@ -175,12 +175,12 @@ public void tick()
             label = computer.getLabel();
             on = computer.isOn();
 
-            if( computer.hasOutputChanged() ) updateOutput();
-
             // Update the block state if needed. We don't fire a block update intentionally,
             // as this only really is needed on the client side.
             updateBlockState( computer.getState() );
 
+            // TODO: This should ideally be split up into label/id/on (which should save NBT and sync to client) and
+            //  redstone (which should update outputs)
             if( computer.hasOutputChanged() ) updateOutput();
         }
     }
@@ -376,11 +376,8 @@ public ServerComputer createServerComputer()
             fresh = true;
             changed = true;
         }
-        if( changed )
-        {
-            updateBlock();
-            updateInput();
-        }
+
+        if( changed ) updateInput();
         return ComputerCraft.serverComputerRegistry.get( instanceID );
     }
 

src/main/java/dan200/computercraft/shared/peripheral/monitor/TileMonitor.java

@@ -148,7 +148,7 @@ public void load( @Nonnull CompoundNBT tag )
     @Override
     public void blockTick()
     {
-        if ( needsUpdate )
+        if( needsUpdate )
         {
             needsUpdate = false;
             updateNeighbors();
@@ -278,8 +278,6 @@ protected final void readDescription( @Nonnull CompoundNBT nbt )
 
         int oldXIndex = xIndex;
         int oldYIndex = yIndex;
-        int oldWidth = width;
-        int oldHeight = height;
 
         xIndex = nbt.getInt( NBT_X );
         yIndex = nbt.getInt( NBT_Y );
@@ -299,13 +297,6 @@ protected final void readDescription( @Nonnull CompoundNBT nbt )
             // If we're the origin terminal then create it.
             if( clientMonitor == null ) clientMonitor = new ClientMonitor( advanced, this );
         }
-
-        if( oldXIndex != xIndex || oldYIndex != yIndex ||
-            oldWidth != width || oldHeight != height )
-        {
-            // One of our properties has changed, so ensure we redraw the block
-            updateBlock();
-        }
     }
 
     public final void read( TerminalState state )

src/main/java/dan200/computercraft/shared/turtle/core/TurtleBrain.java

@@ -160,8 +160,8 @@ private void readCommon( CompoundNBT nbt )
         overlay = nbt.contains( NBT_OVERLAY ) ? new ResourceLocation( nbt.getString( NBT_OVERLAY ) ) : null;
 
         // Read upgrades
-        setUpgrade( TurtleSide.LEFT, nbt.contains( NBT_LEFT_UPGRADE ) ? TurtleUpgrades.get( nbt.getString( NBT_LEFT_UPGRADE ) ) : null );
-        setUpgrade( TurtleSide.RIGHT, nbt.contains( NBT_RIGHT_UPGRADE ) ? TurtleUpgrades.get( nbt.getString( NBT_RIGHT_UPGRADE ) ) : null );
+        setUpgradeDirect( TurtleSide.LEFT, nbt.contains( NBT_LEFT_UPGRADE ) ? TurtleUpgrades.get( nbt.getString( NBT_LEFT_UPGRADE ) ) : null );
+        setUpgradeDirect( TurtleSide.RIGHT, nbt.contains( NBT_RIGHT_UPGRADE ) ? TurtleUpgrades.get( nbt.getString( NBT_RIGHT_UPGRADE ) ) : null );
 
         // NBT
         upgradeNBTData.clear();
@@ -618,16 +618,26 @@ public ITurtleUpgrade getUpgrade( @Nonnull TurtleSide side )
 
     @Override
     public void setUpgrade( @Nonnull TurtleSide side, ITurtleUpgrade upgrade )
+    {
+        if( !setUpgradeDirect( side, upgrade ) ) return;
+
+        // This is a separate function to avoid updating the block when reading the NBT. We don't need to do this as
+        // either the block is newly placed (and so won't have changed) or is being updated with /data, which calls
+        // updateBlock for us.
+        if( owner.getLevel() != null ) owner.updateBlock();
+    }
+
+    private boolean setUpgradeDirect( @Nonnull TurtleSide side, ITurtleUpgrade upgrade )
     {
         // Remove old upgrade
         if( upgrades.containsKey( side ) )
         {
-            if( upgrades.get( side ) == upgrade ) return;
+            if( upgrades.get( side ) == upgrade ) return false;
             upgrades.remove( side );
         }
         else
         {
-            if( upgrade == null ) return;
+            if( upgrade == null ) return false;
         }
 
         upgradeNBTData.remove( side );
@@ -639,8 +649,9 @@ public void setUpgrade( @Nonnull TurtleSide side, ITurtleUpgrade upgrade )
         if( owner.getLevel() != null )
         {
             updatePeripherals( owner.createServerComputer() );
-            owner.updateBlock();
         }
+
+        return true;
     }
 
     @Override