Stop freeze changing license if CSS dialog also used (1.1.x)

Don't rewrite license on read if every node that would be written out already exists and matches. This avoids triggered another update, avoiding an update cascade between Document properties and CSS and Selectors dialogs. Alternative fix to 9ef6758e

Fixes #2700 (closed)

old solution description

If file has CSS styles applied, license change causes CSS dialog to modify the document, which causes the Document Properties dialog to update, which causes the license to change. Alternative to larger fix 9ef6758e

Side effects: warnings logged to terminal. If the Other license is selected, it immediately changes to Proprietary (this was happening before, just not immediately)