In file-stamp cache, accept NIL as filename.
Bump version to 3.1.0.11
Fix special binding problem with dump-image.
Same as for restore-image in 3.1.0.8.
Bump version to 3.1.0.12
UIOP improvements.
Define the :DBG macro, so it's ubiquitously available for print-debugging.
Define and export nest, so it's always there to prevent indentation drift.
Tweak restore-image again for better handling of *lisp-interaction*.
Update docstrings for define-package.
Define %process-info-pid.
Bump version to 3.1.0.13