Add Sphinx documentation

.gitignore

.gitlab-ci.yml

docs/source/_static/images/bar1.png

docs/source/_static/images/bar2.png

docs/source/_static/images/intro.png

docs/source/_static/images/mapping.png

docs/source/_static/images/prediction.png

docs/source/_static/images/results.png

docs/source/_static/images/training.png

docs/source/conf.py

docs/source/example-plain.rst

docs/source/example.rst

docs/source/index.rst

src/gui_version/RandomForest_gui.py