Use Sphinx RTD theme locally as well.
Fix comments in `ref_doc_generation.py`.
Outsource `third-party libraries` section in a separate file.
Fix docstring.
Reformat sections and subsections in documentation.
Add `examples` section.
Breakdown graphics example into smaller program examples.
Break down graphics example and update documentation. (cont'd)
Revert changes in `example.cpp`.
Merge remote-tracking branch 'origin' into maint-update-documentation
Break down examples into separate source code files.
Update Graphics documentation.
Rename Core.rst to core.rst
Rename Graphics.rst to graphics.rst
Move table of contents at the top of the page.
Merge pull request #69 from DO-CV/maint-update-documentation

[MAINT] Update documentation (cont'd)