* Add the initial version of CI using GitHub Actions
* Update .github/workflows/check_pr.yml
Co-authored-by: Wilson Snyder <wsnyder@wsnyder.org>
* remove setting for travis
* rename travis-*.bash to ci-*.bash
* Rename TRAVIS_ variables to CI_
* install ccache and libsystemc(-dev) in ci-install.bash
* Use CI_ variables and Ubuntu-20.04 that provides SystemC
* call ccache maintenance
Co-authored-by: Wilson Snyder <wsnyder@wsnyder.org>