* load-op needn't be sideway, its sideway dependencies are already provided by prepare-op
* compile-op should use compile-op (default) not load-op as its downward-operation.
* no need for an input-files method for prepare-op, nil is the global default.
* Some documentation for compute-action-stamp.
* Don't skip upgrade from 1.x on Allegro anymore, since we now correctly punt.
* Instead of asdf/package:define-package, use the canonical name uiop/package:define-package