Merge pull request #237 from pft/nrcnex

Remove escaped EM tags, keeping only content
pep8
Smarten punctuation: Fix a double quote preceded by a hyphen at the end of a sentence (before the start of the next tag) being converted into an opening quote instead of closing quote. Fixes #1286477 [Smarten punctuation uses wrong character at end of paragraph](https://bugs.launchpad.net/calibre/+bug/1286477)
When deleting books from the calibre library, fix empty author folders not being deleted if they contain system generated cache files, like .DS_Store or Thumbs.db. Fixes #1313452 [[Enhancement] Delete author folders upon removal of only book](https://bugs.launchpad.net/calibre/+bug/1313452)
Use zero-based month as 2nd dynamic field in URL