Complete update of the ontodoc tool

[jesper-friis]

Description

Rewrite and simplify the ontodoc tool such that it is easy to use for both EMMO and EMMO-based domain ontologies.

The new version is based on the solution in domain-battery. For now the python module is called ontodoc_rst.py.

Tasks

• Reproduce all information included in the [battery.rst] (https://github.com/emmo-repo/domain-battery/blob/master/sphinx/battery.rst) file.
  [PR Rewriting ontodoc based on domain-battery #742]
• Add tooling for creating other needed files, like index.rst (just a template that the user can improve).
  [PR Rewriting ontodoc based on domain-battery #742]
• Add a new ontodoc script/tool - instead of adding a new tool, the old ontodoc tool was extended to support .rst output. It doesn't run sphinx automatically, though...
  [PR Rewriting ontodoc based on domain-battery #742]
• Add option to ontodoc to run sphinx automatically
• Add small tutorial of how to use the tool
• Add ontology metadata documentation to generated documentation
• Add more semantic information to generated documentation
• Add language to keys for localised values
• Add default css file (common for all EMMO domain ontologies, could e.g. be downloaded from a common source...)
• Add support for figures (e.g. by displaying links to known image formats as images)
• Sort modules in a logical order, e.g. by namespace and import depth
• Add a module dependency graph at the top
• Add subclasses to generated documentation to support navigating the taxonomy
• Is it possible to collapse the sidebar to make it easier to navigate to the right module?
• Add anchor by prefLabel, to make it easier for people to find the IRI when one knows the prefLabel

---

Structure the generated document as follows:

==========
References
==========

Module: <first_module_name>
===========================

-------
Classes
-------

<class1>
--------

...

For each module, document:

• classes
• object properties
• data properties
• annotation properties
• individuals
• datatypes