pep8
Fix smarypants test runner
Smarten punctuation: Correct handling for decade abbreviations like '60s and measurements in feet and inches like 1' 2". Fixes #1285351 [Edit Book: Smarten Punctuation handles years and measurements incorrectly](https://bugs.launchpad.net/calibre/+bug/1285351)
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Metadata download: Add an option to merge the downloaded comments into existing comments, instead of overwriting (Preferences->Metadata download). Fixes #1285319 [[Enhancment] Enable Undo in the comments field](https://bugs.launchpad.net/calibre/+bug/1285319)