Use “fill”, not “stroke” to set the color of the text elements.
Like this the stroke numbers don’t get a bold-like look.
Fix the tests for the stroke→fill change.
Update README

* Development note (including how to run tests)
* Current Anki situation (Anki2 is out; forget Anki1.  However there is
  a major known issue with the Anki2 addon.)
* Note about github downloads being depricated
* Typoes