#72 Saved layout does not always preserve "pinned" state

See last paragraph of reported issue with MyDoggyPlugin in jEdit:
https://sourceforge.net/tracker/?func=detail&aid=2831755&group_id=588&atid=565475

When saving a layout, the "pinned" state (pinned or unpinned) should be part of the saved layout, and should be restored when the layout file is read.