Make logging from modules easier

[rlerm]

This is somewhat related to https://github.com/ultrabug/py3status/issues/1479, in which more control of logging was requested, with per-module granularity. The proposal here is to just use the builtin logging module, instead of self.py3.log.

IMO, this will be easier for module authors since it's a more standard interface, and allows per-module configuration out of the box.

The most important use case this will enable is for debugging only a specific module, since you'll be able to enable higher logging levels without getting spammed by others.

[ultrabug]

Thank you @rlerm this is a very interesting proposal.

I will write down my remarks on #2064