Add function widgetNode, a simpler and more efficient alternative to

Add function widgetNode, a simpler and more efficient alternative to
findnode for most though not all purposes. widgetNode('Records') is
equivalent to findnode('.mkwsRecords') but works by reference to the
team's registered set of widgets.

This is presently used in just one place, as proof of concept. Many
more to follow, so that uses of findnode should become very rare.