Implement mn-requirements as a configurable reader/renderer for requirements models

[ronaldtse]

The following questions should be addressed:

1. How do I specify a new data model for requirements? (e.g. ISO's version)
2. How do I enter instances for that data model? (presumably simplest using YAML/hash and provide a defined mapping from MN Adoc to YAML/hash)
3. How do I specify the rendering of a model into Presentation XML (e.g. into a table) (presumably liquid)

https://github.com/metanorma/iso-19135 should be used as an example for this work.

[opoudjis]

This is massively premature, and naive.

[opoudjis]

I'll document the gem methods, and I'll consider Liquid, although I'm not confident it will work in general. But I need to be allowed to get the refactoring of requirements out of standoc and ogc done at all first.

How instances are entered for the data model is a solved problem within Metanorma AsciiDoc, and any YAML integration is outside my responsibilities.

[ronaldtse]

YAML is can just be a hash representation of the data model.