Ticket #3091: iso9660: fix truncated filenames.

±1 problem results in truncating filenames in ISO file listing. This
commit fixes the issue.
Ticket #3092: fix some minor manual formatting errors.

  * "OnDumbTerminals" appears as one word.
  * Unnecessary linebreak at "Vertical or Horizontal" (under Panel split).
  * Inconsistency: some dots missing.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>