Python core logging

Summary

Adds a logger for python core

Related Issues

• Closes #216 (closed)

Documentation

Checklist

• All code changes are covered by unit tests
• Code coverage did not deteriorate
• Code follows Style Guide
• Documentation updated, if necessary (needs to be done in the course of #211 )
• WIP: Manual running of configure/build jobs was successfull
• Update version info, if changes are worth mentioning (Develop section in doc/src/version_info.dox, add section if not yet included)