revise console output

[patkan]

This library has some outputs that would be ok as a console output for the script interface, but should not be printed to the console if called as a library.

Proposal:
Change print calls to logging calls. For the library the default log level should be warning, for the cli it should be info.

[patkan]

Not necessary to get v3.0 out, therefore removed from Milestone (can be done later)