* pgg-gpg.el (pgg-gpg-shell-command-switch): New user option.

* pgg-gpg.el (pgg-gpg-shell-command-switch): New user option.
(pgg-gpg-process-region): Bind `shell-command-switch' to the value
of `pgg-gpg-shell-command-switch'.

* pgg-pgp.el (pgg-pgp-shell-command-switch): New user option.
(pgg-pgp-process-region): Bind `shell-command-switch' to the value
of `pgg-pgp-shell-command-switch'.

* pgg-pgp5.el (pgg-pgp5-shell-command-switch): New user option.
(pgg-pgp5-process-region): Bind `shell-command-switch' to the value
of `pgg-pgp5-shell-command-switch'.

* pgg-gpg.el, pgg-pgp.el, pgg-pgp5.el (sign-region): Use fixed end
position of the signature.