Notable changes

• Add Mastodon support!
• Add Python 3.7 support, and improve overall Python 3 compatibility.
• Update a number of dependencies.
• Switch from Python's built in json module to ujson to speed up JSON parsing and encoding.
• Add duration and size support to ActivityStreams 1 and 2, RSS, and microformats2 HTML and JSON. microformats2 support is still emerging for both. Both integer seconds and ISO 8601 string durations are supported for duration. Integer bytes is used for size everywhere. microformats2 HTML also includes human-readable strings, eg 5.1 MB. (#169)
• Twitter:
  • [preview]_create(): detect attempts to upload images over 5MB and return an error.
• Facebook:
  • Add get_activities(scrape=True) for scraping HTML from m.facebook.com. Requires c_user and xs cookies from a logged in session (snarfed/bridgy#886).
  • Upgrade Graph API version from 2.10 to 4.0.
• Atom:
  • Bug fix for de-duping images in attachments.
• RSS:
  • Wrap all <description> element contents in CDATA sections.
  • Render images in <description> with HTML <img> tags (#175).
  • from_activities() bug fix: don't crash when converting multiple attachments to enclosures in a single item. (RSS only supports one enclosure per item, so we now only include the first, and log a warning if the activity has more.)