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)

python/src/deltachat/account.py

@@ -546,6 +546,9 @@ class Account(object):
         You may call `stop_scheduler`, `wait_shutdown` or `shutdown` after the
         account is started.
 
+        If you are using this from a test, you may want to call
+        wait_all_initial_fetches() afterwards.
+
         :raises MissingCredentials: if `addr` and `mail_pw` values are not set.
         :raises ConfigureFailed: if the account could not be configured.