imap-proto 0.11.0

This release contains numerous internal improvements and some hopefully minor API changes.

• Add workaround for Zoho Mail invalid FLAGS response (#91, thanks to @link2xt)
• Add support for RFC 5161 ENABLED extension (#85, thanks to @mordak)
• Add parser for HEADER.FIELDS (#72, thanks to @link2xt)
• Lots of refactoring to make the parsers easier to navigate (#81, #82, thanks to @duesee)