big manpage update by Herve, including:

big manpage update by Herve, including:
- TTL target had nothing to do here, as it is in patch-o-matic.
  Deleted for coherence. Maybe we could have a special manpage for
  extra extensions, but as they are already documented in the
  Netfilter Extensions HOWTO, it would seem to appear as a
  duplicated effort.
  I just added a note on the existence of this HOWTO.
- check option (former -C in ipchains) will never exist (document this
  in the FAQ, if not done)
  - owner section was duplicated in the process of merging my previous
    manpage patch (a bug in the patch tool? ;-)
  - small typo fixed
  - some minor cosmetic changes