Feature/documentation build

Description

Implements the documentation build system based on sphinx with read-the-docs theme.

Changelog:

• Provide sphinx configuration with required extensions
• Include markdown CONTRIBUTING and DEVELOPERS files
  • Note: toc tree and some links are messed up. Fix TBD
    • problem: it is not possible to have working representation both for GitLab and for recommonmark due to anchoring and referencing differencies. Currently keep GitLab anchoring.
• Include Jupyter notebook as user story
• Provide API doc and cleanup comments in the code

Related Issue

Closes #10 (closed)

How Has This Been Tested?

The documentation has been built in local virtual environment. Uploaded for testing and looking around here

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.