Percentage as first class progress indicator

There are editions where pages are not yet known. Obviously you could hack this by falling back to 1000 pages (what I've done locally for a koinsight server for backwards compatibility).

For any given quantity of unstructured text I can tell you what percentage I am through the text even without known the pagination of the text. It would be great if this were supportable!

The UI doesn't gracefully degrade right now.