Copy content via GUI, by clicking a button?

Problem/Motivation

Importing via Drush works well, but for some users, it might be easier to do the copying between source and target via the GUI, by clicking a button.

It could be via a new option "Import" under the individual Field updaters Operations drop-down, or some other way?

Proposed resolution

Add an "Import" button under each Field updaters Operations drop-down.

Or perhaps a dedicated "Import" tab is better?

Remaining tasks

User interface changes

API changes

Data model changes