GitLab

* Refactor setup.py to build only wanted extensions.

* Improve visual feedback for libpng support in setup.py.

* Improve printing of extensions finding in setup.py.

* Fix linter errors.

* Apply suggestions from code review
Co-authored-by: Vasilis Vryniotis <datumbox@users.noreply.github.com>
Co-authored-by: Vasilis Vryniotis <datumbox@users.noreply.github.com>