Add developer guideline for testing warnings
Fix PEP8 in io.ascii with autopep8 --max-line-length=100
Fix a few places where autopep8 made a bad choice
Merge pull request #1239 from taldcroft/doc/test-warnings

Add developer guideline for testing warnings
Merge pull request #1240 from taldcroft/ascii/pep8

Fix PEP8 in io.ascii with autopep8 --max-line-length=100
WIP
WIP