Update copy_pages to move illustrations to destination

[srjfoo]

Project Managers sometimes include missing illustrations with a missing pages project, not as a separate zip. The problem lies in the fact that the illustration might be deleted if the squirrel running the MP project is not aware it's there.

It would be helpful to the squirrels to have the script check for the presence of non-page images, and move them from the source to the destination project if there are no filename conflicts, and to provide a list of any conflicts, at least.

There may need to be some design discussion to figure out how to handle the situation where the filename duplicates an existing filename -- assume that it's okay to overwrite, or should the squirrel be warned to verify that manually, and the script just issue a warning as a reminder to the squirrel that there's a non page image there?

There may be other edge-cases that should be taken into consideration.