Describe the Bug

Because we try to normalize the page content before saving it to the database in a format different to the one that tinymce exports, django always reports that the content field changed (except on empty pages), even when just clicking "Update".

This should largely be fixed by #2668

Steps to Reproduce

1. Go to a page with >1 lines of content
2. Compare the source in tinymce with the content in the database (e.g. via django admin) → They are different (e.g. <br> vs. \r\n)
3. Click on Update

Expected Behavior

The page should show No changes detected, but date refreshed

Actual Behavior

The page shows Page "<page name>" was successfully updated