Marko

- Add pretty representation for the AST for debugging purpose. An extra group `repr` is added for more readable output.
- Make a dummy `Document` element if the element to render is not a `Document` instance.

Fixed

- Rewrite the parsing logic of GFM tables.
- Fixed the dispatching among different renderers for render methods in extensions. Now the GFM renderer supports `MarkdownRenderer`.

Fixed

- Preserve link references when rendering document as Markdown.

Documentation

- Fix the sidebar warning in shibuya theme.

Changed

- Avoid saving to global variables during parsing. There can be multiple parsers running in parallel.
- Now the `children` attribute for block elements should be a list of child elements.
- Move the HTML content of `HTMLBlock` from `children` to `body` attribute.
- Fixed some built-in extensions that modify class attributes.
- Add a helper class to create extensions, instead of using arbitrary objects to hold partial properties.

Fixed

- Call `setup_extensions()` when running `render()` method alone.

Fixed

- Fix the unpack error when parsing a fenced code block with `codehilite` extension enabled.

- Fix a bug that `Parser.parse_inline()` cannot be called without preceding call of `Parser.parse()`. [131](https://github.com/frostming/marko/issue/131)
- Fix a rendering bug when line breaks exist in a link text. [126](https://github.com/frostming/marko/issue/126)
- Drop support of Python 3.6.
- Update the GFM spec to the latest master branch.
- Fix a precedence issue of parsing strikethroughs in GFM.