* src/gpgoladdin.cpp (GpgolRibbonExtender::GetIDsOfNames): Register
new names.
(GpgolRibbonExtender::Invoke): Handle new names.
(GetCustomUI_MIME): Reactivate Read code. Use new callbacks.
(Mail::Mail): Do not cache sig validity.
(Mail::get_valid_sig): Get Sig / UID pair of the valid sig.
(Mail::is_valid_sig): Use get_valid_sig.
(Mail::is_signed): Fix use of temporary parser object.
(Mail::set_uid): Set uid to be identifyable from callbacks.
(Mail::get_signature_status): Format string for supertip.
* src/mail.h: Update accordingly.
* src/ribbon-callbacks.cpp (get_crypt_status): Removed.
(get_mail_from_control): New. Helper to resolve the Mail object.
(MY_MAIL_GETTER): Helper macro for common task.
(get_is_signed, get_sig_label, get_sig_ttip, get_sig_stip): New
callbacks.
(launch_cert_details): Dummy.