Removes redundant copies of images and reassigns materials using them. Frees up memory.
Works best on big projects where multiple files are appended into a render file creating redundant copies of images.
Works based on images in the file with names like: image_name.png.001.
Once installed a tab in the "N" panel in the 3D view is created with a single button: "Cleanup."
Also kills all orphan data to further free up memory.