Replace TravisCI with Github Actions

[belochub]

This also enables builds on push to master to keep the badge in README.md relevant.

• [x] code is properly formatted (npm run fmt)
• [x] documentation is updated (npm run doc to regenerate documentation based on comments)

[belochub]

Landed in https://github.com/metarhia/common/commit/c360812cdce50461d93158f2e015e856f96b9b88 and https://github.com/metarhia/common/commit/f31151cffd06452735a566eedcbff253645e6917.