- 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

Cargo.toml

@@ -30,6 +30,7 @@ serde_json = "1.0"
 chrono = "0.4.6"
 failure = "0.1.5"
 failure_derive = "0.1.5"
+indexmap = "1.3.0"
 # TODO: make optional
 rustyline = "4.1.0"
 lazy_static = "1.4.0"