Include the in installation section in doxec CI execution to check that the
installation paths are correct.

Use args.f instead of args.format which is not available.

Don't print anything, if output is missing and the input is not valid.

Add a single CI job, which runs the unit tests.

Add initial version including command line tool and unit tests.

Add a readme file which outlines the initial idea of c-shelve and its use case.