- Reorder parser methods and use `Pos` everywhere
- Remove tab special handling for columns and adapt heading/list/enum indent handling
- Don't panic when a file has an empty path
- Unordered lists with indent-based parsing and basic layout using stacks
- Headings are now also indent based
- Removes syntax functions since they will be superseded by select & transform
This adds overridable functions that markup desugars into. Specifically:
- \ desugars into linebreak
- Two newlines desugar into parbreak
- * desugars into strong
- _ desugars into emph
- = .. desugars into heading
- `..` desugars into raw
