- create and use a ContactIds type as an ordered set instead of "Vec<u32>".

- recreate the group list more carefully, fixes #985

- resultify a few functions in the dc_receive pipeline

- don't quote displaynames in email-addresses, use utf8, preliminrarily addresses #976

src/mimefactory.rs

@@ -394,7 +394,7 @@ impl<'a, 'b> MimeFactory<'a, 'b> {
                 to.push(Address::new_mailbox(addr.clone()));
             } else {
                 to.push(Address::new_mailbox_with_name(
-                    name.to_string(), 
+                    name.to_string(),
                     addr.clone(),
                 ));
             }