Summary:
- Remove thread_participants prop, we don't use them anywhere and the underscore-case is ugly.
- Move autolinker into extension, update autolinker to 0.18.1 for phone number support
- document message.coffee, add isFromMe()
- Add tracking pixel extension that removes pixels from mail you *send*. Maybe more features later.
Test Plan: Run 1 new test! (woo...)
Reviewers: evan
Reviewed By: evan
Differential Revision: https://phab.nylas.com/D1787
