[Code] [Server] [GUI] Toggle image displays on/off

[alathon]

The gist of this is to provide a 'Visual debugging' mode, where the Image boxes are used, and an alternative 'Non-debugging' mode, where we no longer need to retain or show images. This will (potentially) save some CPU.

[alathon]

This should affect FilteredImage, as instead of retaining a balance image, current image, diff image and result image, all we need are balance and current.