Closing connection manually

[radekbenkel]

I see, that code is missing explicit closeImapStream (or similar) method - sometimes you may want to close connection and open it once again in one script, while creating new object is tricky (for example, Fetch is your class dependency already configured and injected from outside).

I can provide PR if you want for that, or just close this issue if you think it's not needed:)

PS. Yes, I found those: #59, #62, #69 - but it was about destructor.