Fix paths in generated pkgconfig file

New Contributors:

- @tgerbet (!168 reviewed by @tranzystorekk)

This bugfix release

- Replace our own unit test framework (CuTest) by
  [Unity](https://www.throwtheswitch.org/unity)
- Do not install tests but make them execute in build directory
- Build and run tests and examples on Windows CI runner
- Fix pkgconfig file

Merge branch 'feature/cmake'

Bump version, introduce Semantic Versioning (https://semver.org)

Bump version

Bump version

Release 4.0

Release 3.2

version 3.1