Feature: Use module path + class name for loggers and init once

[penguinolog]

• Add logger to all Widget instances (if properly subclassed)

Checklist

• I've ensured that similar functionality has not already been implemented
• I've ensured that similar functionality has not earlier been proposed and declined
• I've branched off the master or python-dual-support branch
• I've merged fresh upstream into my branch recently
• I've ran tox successfully in local environment
• I've included docstrings and/or documentation and/or examples for my code (if this is a new feature)

[coveralls]

Pull Request Test Coverage Report for Build 7336966911

• 3 of 7 (42.86%) changed or added relevant lines in 2 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+0.003%) to 71.017%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
urwid/display_common.py	0	1	0.0%
urwid/widget/widget.py	3	6	50.0%

Files with Coverage Reduction	New Missed Lines	%
urwid/_raw_display_base.py	1	6.2%

Totals
Change from base Build 7336954258:	0.003%
Covered Lines:	7596
Relevant Lines:	10794

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💛 - Coveralls

[wardi]

this logger could be part of the class instead of the instance so it doesn't have to be tracked in every single widget

[penguinolog]

It will require metaclass usage, which is a bit overkill

[wardi]

It could also be a Widget property or method that returns the logger

[penguinolog]

Technically once logger initializer, it stored in logging.Manager, so all instances of the same Widget class uses the same Logger.
Adding property may break downstream, because it will cause errors if downstream initialize logger itself.