wks: Add command --read to gpg-wks-client.

* tools/gpg-wks-client.c (aRead): New.
(opts): Add command "--read".
(main): Implement that.

This command allows to process alread decrypted Web Key Service
messages. It can for example be used in /etc/mailcap

--8<---------------cut here---------------start------------->8---
application/vnd.gnupg.wks; gpg-wks-client -v --read --send;\

needsterminal; description=Web Key Service message

--8<---------------cut here---------------end--------------->8---

to allow Mutt to process confirmation requests.

• Signed-off-by: Werner Koch <wk@gnupg.org>