Python interface for functionality

[felix-schott]

Description

I think a proper python interface would be nice to have, in addition to the CLI.

The following things should probably be changed, just gathering my thoughts here:

• find a more descriptive name for function download()
• use python logger instead of click.echo() - this removes the need for a bunch of flags for the download function like silent, as this is all handled by the built-in python logger. Using the python logger allows users to register their own handlers more easily. The CLI can simply translate flags into logger settings.
• ...

I might make a PR when I have time, just wondering if you have any thoughts on this.