had numerous problems, the main one being that each of the three
commands was inconsistent: "expand toggle" inverts the expansion
of the selection and syncs with the layout. But "expand" expands
the layout where instances overlap the box and does not sync to
the selection, and "unexpand" unexpands the layout where the box
completely surrounds instances. Added a set of options to
"expand" and "unexpand" so that these functions can be made
consistent with each other. All varieties of the function now
always sync the selection and the layout.