(format-encode-run-method): Fix error message to say

(format-encode-run-method): Fix error message to say
`encode' instead of `decode'.  Use save-window-excursion around
shell-command-on-region as in format-decode-run-method because
shell-command-on-region can display a buffer with error output.
(format-decode): Don't record undo information for the decoding.
(format-annotate-function): Add parameter FORMAT-COUNT.  Make
that number part of the temporary buffer name so that more than
one decoding using a temporary buffer can happen safely.