* .gitlab-ci.yml: Install apt dependencies quietly.

* .travis.yml: Fix build config warnings and update Python versions. Deprecate it.

* docs/markdown/stylesheets/extra.css: Updated to work with changes
to mkdocs-material.

* requirements.txt: Update dependencies.

* README.md: Update links.

* setup.py: Mark development status as 'Production/Stable'.

* tests/freetype.sh: Clone from Gitlab.

* tox.ini: Update Python versions.