Pandoc AST reader

[drehak]

Implementing support for Pandoc's intermediate output (elements of its abstract syntax tree, or AST) would enable Lunamark to conver all input formats supported by Pandoc. Using Pandoc to first convert the input to Markdown and then run it through Lunamark wouldn't be viable, since Markdown as a format can't output all of Pandoc's elements. Therefore, a new reader will be necessary for this.

While a basic prototype is functional, there are still some things that need to be done.

This list is incomplete; you can help by expanding it.

• Implement all Pandoc elements #3
• Add sensible generic outputs for all Pandoc elements #4
• Rebase on current Lunamark master

(This was originally intended to bring the support for Pandoc's AST to the Markdown LaTeX package, which is built on top of Lunamark. Since starting the work on this prototype, we have opted for a solution based on a custom writer for Pandoc instead. However, someone could still benefit from this.)