#20 need better error message for garbled pgp formats

[Holger Schurig]

When a user sends a public key and some mailserver garbles
the text, then the user just sees the error message

"Key format error"

That's correct, but the underlying error message from GPG is more self-explaining, tellquoted printable character in armor - probably a buggy MTA has been usedging the user

"quoted printable character in armor - probably a
buggy MTA has been used"

So I should change the source to give a better error message back to the user.