Special case: in case of Columns/Pile empty - use fallback sizing

[penguinolog]

• Extend repr to provide brief info about contents

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 8050646553

Details

• 0 of 16 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.03%) to 72.581%

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Totals
Change from base Build 8045394934:	0.03%
Covered Lines:	9143
Relevant Lines:	12670

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💛 - Coveralls