* now fix NB#78955:

* now fix NB#78955:
	- choose the right MIME-part for the body, with breaking
          messages which worked before
	- display 'inline' mime parts as attachments, if we don't
	  display them otherwise
	- create modest-tny-mime-part.[ch] as our TnyMimePart decorator

- do we need to use the new
		modest_tny_mime_part_is_attachment_for_modest
	  in other places too?

pmo-trunk-r3984