Implement encryption without MAPI data
* src/attachment.cpp (Attachment::get_data_string): New helper. * src/attachment.h: Declare get_data_string. * src/mail.cpp, src/mail.h (Mail::remove_attachments) (Mail::add_attachments, get_string, Mail::get_body) (Mail::get_html_body, Mail::get_recipients): New. * src/mailitem-events.cpp (request_send): Comment out for now. (EVENT_SINK_INVOKE): Encrypt in send event. * src/mimemaker.cpp (sink_data_write): New to work with GpgME::Data. (encrypt_sign_mail): New works based on Objects.
This still uses the engine style encryption. In this first impl
only encryption is supported. Can do both inline and MIME.