Add `ddeboer/imap` (#1210)

* Add ddeboer/imap

* AlphaSort

README.md

 *Libraries for sending and parsing email.*
 
 * [CssToInlineStyles](https://github.com/tijsverkoyen/CssToInlineStyles) - A library to inline CSS in email templates.
+* [ddeboer/imap](https://github.com/ddeboer/imap) - Object-oriented, fully tested PHP IMAP library.
 * [Email Reply Parser](https://github.com/willdurand/EmailReplyParser) - An email reply parser library.
 * [Email Validator](https://github.com/nojacko/email-validator) - A small email address validation library.
 * [Fetch](https://github.com/tedious/Fetch) - An IMAP library.