Implement module scoped logging

[MaxDall]

Since #357 rewrites a huge part of the core pipeline, this PR is based on the redesign and should be merged afterwards.

This removes the central logging solution of basic_logger and implements module-scoped logging. Every module utilizing logging must now have its own logger called __module_logger__.

from fundus.logging import create_logger

__module_logger__ = create_logger(__name__)

One can set a global log level

import logging
from fundus.logging import set_log_level

set_log_level(logging.DEBUG)

effecting only loggers created with create_logger, or setting the log level of individual module-scoped loggers by importing them.

import logging
from fundus.scraping.html import __module_logger__

__module_logger__.setLevel(logging.DEBUG)

[dobbersc]

This definitely works. But I wondered if such a setup is possible where each module can just call logger.getLogger(__name__) to get their module logger, just like in the python logging guide. I failed to get this to work but wanted to give the idea here. Maybe you tried this as well?

[MaxDall]

Good idea. The only problem is see is how we set the log level for all Fundus logger at once? Setting them individually wouldn't be a problem, but I have no solution for how we would set the whole library to DEBUG without keeping track of the loggers.

[dobbersc]

Yes, that was also a problem I encountered. I found this comment but haven't been able to get this working. I would merge this for now as is and maybe try later.