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/mimeparser.rs

@@ -1286,9 +1286,9 @@ fn get_attachment_filename(mail: &mailparse::ParsedMail) -> Result<Option<String
 }
 
 /// Returned addresses are normalized and lowercased.
-fn get_recipients(headers: &[MailHeader]) -> Vec<SingleInfo> {
+pub(crate) fn get_recipients(headers: &[MailHeader]) -> Vec<SingleInfo> {
     get_all_addresses_from_header(headers, |header_key| {
-        header_key == "to" || header_key == "cc"
+        header_key == "to" || header_key == "cc" || header_key == "bcc"
     })
 }