(pgg-pgp-messages-coding-system): New variable.

(pgg-pgp-messages-coding-system): New variable.
(pgg-pgp-process-region): Use `binary-to-text-funcall' instead of
`binary-start-process-shell-command'.
(pgg-scheme-verify-region): Use `binary-write-decoded-region' instead
of `binary-write-region'.

;; Ueno-sama, please forgive me.