Updated the
first post with a much-needed update to the plugin. It uses the new preferences functionality that Sigil 0.8.3 provides and so
Sigil v0.8.3 is, in fact, the minimum version necessary to use the plugin.
Also tweaked smartypants' regex to deal better with unicode characters (thanks @tempura).
It will work with either Python 3 (3.4 or higher) or Python 2.7.