dry run: do not (try to) upload file, without dumping

[blueyed]

You can use -d to dump the upload file instead of uploading, but that is quite verbose.

It would be nice if -d would just output the URL, and only -v -d would dump it - given that a long option like --dry-run is not trivial to do with bash's getops (but would be possible), and that -n is already taken.

Via #86.