All state held in that class is apparently now moved to the
ParserCombinator which uses the serialized output

Possibly change all methods in the class to be class/static methods
instead in the future.

As a steping stone, the raw match data was emited to the frontend. This
just properly renders it.

If `parse_puppet` crashed, instead format the the raw code, adding an
error marker on the erroring character if possible. The error message is
also added.

Previously the the input json was directly mapped into the output
strings, through different formatters. This changes it so we instead
first build a proper AST of python objects, which is later mapped to
output strings (still through formatters).

This gives us much better type information, and will give way to much
more advanced formatters in the future.

This includes some regressions:
* Docstrings aren't handled as well
* The code lacks any form of hyperlinks.

Misc includes:
    - at least one more category
    - basic sidebars

See static-src/README.rst for details about how it works.

Python-commonmark is deprecated, and recommends markdown-it-py instead.

This commit also introduces an abstract muppet.markdown module to allow
easier switching in the future, and enables id's for all headers in the
generated HTML.

Documentation can now be generated to HTML through sphinx.
Some docstrings have been updated to be on the correct format.

- Moved most datatypes to own modules
- changed output to take a generator instance for multiple output forms
- Wrote tests for the "parser"
- fixed some bugs revealed in the parser while writing those tests.