[vxzqvibu] Manual permutations

Create a generic UI that allows drag and drop reordering of a collection of labeled squares.  Select and move several consecutive squares at a time.

(Another tool generates the squares with text or image labels.)

Line breaks, different levels of indentation might be useful: this is essentially text editing.

Need some interface to be able to do things with the ordering, or with individual squares.

Inspired by creating music playlist.