1.x-2.0.0

This is a major re-write of the module, incorporating many new features and bug fixes from the issue queue but significantly changing how the API and cache works.

• Ported to Backdrop CMS
• Incorporated either as is (but ported to Backdrop) or with modifications the following patches:
  • regex not working | patch by chrisfromredfin | Used as is
  • Support authenticated API requests | patch by chrisfromredfin | Updated to use tokens and porting changes.
  • Improve Error Reporting | patch by chrisfromredfin | Used as is
  • Embedding on HTTPS sites | patch by arnested | Used as is
  • Allow usage of all three display methods at once | patch by MaskyS | This was actually a D8 patch, but was able to upgrade to Backdrop CMS. I also changed it to support using the default method for the text format in addition to the override codes.
• Modified how the module works with the cache. Gist Filter now has its own cache and only re-fetches from the API if the gist has changed, saving on API calls for big sites with lots of gists.
• Allow clearing the gist cache
• Allow disabling of separate noscript code version of gist.
• Modify the default display method that is used for new text formats.
• Added themes for the embed method.

Full Changelog: https://github.com/backdrop-contrib/gist_filter/commits/1.x-2.0.0