handlebot 0.0.9

This is a non-breaking release. Here are the most interesting changes:

- Now any transport supported by urlpreview supports any format
  supported by urlpreview. That means you can serve HTML from a Gemini
  server, or Gemtext from an HTTP server, and handlebot will fetch
  previews for both of them just fine.

- Proper XHTML support was added (to all transports).

- Help was moved away from the bot interface to README.md.

Umar Getagazov (8):
      Update README
      Remove help
      Vendor girc differently and upgrade dependencies
      Refactor urlpreview out and remove some bloat
      Implement handlebot-specific previewers
      Remove useless sync.WaitGroup
      Better text truncation routine
      Join IRC channels in bulk