Peek reipients, fetch existing messages

Read all of an e-mail accounts messages and extract all To/CC addresses
if the From was from our own account.
Then, fetch existing messages from the server and show them.

Also, I fixed two other things:
- just by chance my test failed because of an completely unrelated bug.
The bug: bcc_self messages were not marked as read if mvbox_move was set
to true.
- add some color to the test output (minor change)

src/config.rs

@@ -121,9 +121,9 @@ pub enum Config {
     #[strum(serialize = "sys.config_keys")]
     SysConfigKeys,
 
-    #[strum(props(default = "0"))]
     /// Whether we send a warning if the password is wrong (set to false when we send a warning
     /// because we do not want to send a second warning)
+    #[strum(props(default = "0"))]
     NotifyAboutWrongPw,
 
     /// address to webrtc instance to use for videochats