* guix/scripts/package.scm (%options): Adapt option processors to accept and
return a second seed value: 'arg-handler', which handles bare arguments (if
not false). The install, remove, and upgrade option processors return an
arg-handler that repeat the same operation. All other option processors
return #f as the arg-handler. Make the arguments to install and remove
optional. The upgrade option processor deletes (upgrade . #f) from the
alist before adding a new entry.
(guix-package): Procedures passed to 'args-fold*' accept the new seed value
'arg-handler'. The 'operand-proc' uses 'arg-handler' (if not false).
* doc/guix.texi (Invoking guix package): Update docs.
* tests/guix-package.sh: Add test.