Removed obsolete html_use_smartypants Sphinx option.

docs/conf.py

@@ -52,8 +52,6 @@ extlinks = {
 # Add it only if spelling check is requested so docs can be generated without it.
 if 'spelling' in sys.argv:
     extensions.append("sphinxcontrib.spelling")
-    # Workaround for https://bitbucket.org/dhellmann/sphinxcontrib-spelling/issues/13
-    html_use_smartypants = False
 
 # Spelling language.
 spelling_lang = 'en_US'