Wagtailcodeblock

* Injects an event into the editor `textarea` to force a resize.
* Makes `WAGTAIL_CODE_BLOCK_LINE_NUMBERS` a new setting; set it to `False` if you'd prefer not to have line numbers show up.

* Only supports Wagtail 2.13 or greater; for previous version of Wagtail, please use `wagtailcodeblock<1.25.0.0`.
* Support for Wagtail 2.13 and above, and conversion to telepath. (cybelew)
* Major performance improvements: (FlipperPA)
* All JavaScript assets are now pulled from CDNJS.
* Only the necessary assets are loaded for the languages highlighted in a page.
* This will save about 500 KB of assets required to load the page.
* This will also save about 1.5 seconds of load time per code block on a page, as PrismJS is only loaded once per page, instead of once per block.
* Initial work for removal of jQuery; this will be completed in the next release.

* Ensure compatibility with new ReactJS StreamFields with Wagtail 2.7.
* Update to PrismJS 1.17.1
* Add pytest-django for a basic test suite.
* Switch to using `setuptools_scm` instead of a `MANIFEST.in` file. Use tagging for PyPI version.

* Update to PrismJS 1.15.0
* Bug fix: do not key off of `Language` label, as it is translatable.

* Upgrade to PrismJS 1.14.0
* Allow passing a language code as an attribute, only allowing the single language to be used.
* Fix conflict in CSS between `tag` class for Wagtail and markup syntax types.

* Upgrade to PrismJS 1.11.0
* Changed version numbers to match the included PrismJS release
* Patch to add support for natively included PrismJS languages ['html', 'mathml', 'svg', 'xml']