(enriched-initial-annotation): Use `fill-column' rather than
enriched-text-width.
(enriched-mode): Use `add-to-list'. Turn use-hard-newlines on by
calling function, not setting variable.
(enriched-encode): New argument ORIG-BUF; evaluate
enriched-initial-annotation in that buffer.
(enriched-decode): Turn on use-hard-newlines with function. Use new
`set-hard-newline-properties' function. Set fill-column from
File-Width header; re-fill paragraphs only if there is no File-Width
header.