* guix/scripts/lint.scm: New file. Defines a 'lint' tool for Guix packages. * tests/lint.scm: New file. * Makefile.am (MODULES, SCM_TESTS): Add them. * po/guix/Makevars: Update appropriately. * po/guix/POTFILES.in: Update appropriately. * doc/guix.texi: Document "guix lint".