Improve output log

[d-krupke]

The current log is only interesting for developers, not for users. Replace it with a better system.

[d-krupke]

Now uses the logging library. It will either use the logger SampLNS or accepts a passed logging.Logger object. The logging of the CDS-part is still done to stdout, and needs to be fixed by @gabriel-gehrke by adding a log callback to the interface.

[d-krupke]

The logging of the C++ components has temporarily been removed, until a proper logging callback or similar has been implemented. Possibly, a pure callback is not feasible with parallelization. Could lead to a deadlock.