Exchange flourish fMailbox with ddebeur/imap
What does this MR do?
libflourish fMailbox has shown problems handling quoted printable email subjects, so it did not fetch some emails from our upstream email inbox.
This MR uses a more modern library instead, hopefully getting rid of that problem.
How confident are you it won't break things if deployed?
I will manually test in beta. We tried adding imap integration testing but decided against it because it is more a one-off test that is easier manually.
Links to related issues
- added a test, or explain why one is not needed/possible...
- no unrelated changes
- asked someone for a code review
- joined #foodsharing-beta channel at https://slackin.yunity.org
- added an entry to CHANGELOG.md (description, merge request link, username(s))