lib/util.sh: zip/unzip_newer: support extracting/updating the file even if it has an older mtime by setting $force, using new set_inv to get a var to use to determine whether to include the -u flag
lib/util.sh: zip/unzip_newer: support extracting/updating the file even if it has an older mtime by setting $force, using new set_inv to get a var to use to determine whether to include the -u flag