To be activated by macro Libisofs_with_checksumS.
New AAIP attributes "isfs.ca" and "isofs.cx".
New API calls iso_image_get_session_md5() and iso_file_get_md5().
and using these numbers in PX entries during next image generation.
This also answers the concerns about PX without ino in RRIP 1.12
and PX with ino in RRIP 1.10 images produced by mkisofs.