This is a fairly intrusive rewrite.
- I pulled the common code for the signature and citation case out
into a separate function. This is not so much shorter, but I think it
will be easier to maintain.
- I replaced the sequence of (looking-at blah) (forward-line) with a single
re-search-forward per citation.
New variables
- notmuch-show-signature-button-format, notmuch-show-citation-button-format
Allow customization of button text.
- notmuch-show-citation-lines-min
Do not buttonize citations below the given threshold.
Reviewed-by: Kan-Ru Chen <kanru@kanru.info>