In case anyone is interested, the $N-Protractor algorithm was ported to Python for use in the Kivy framework [0]. Unfortunately it's tied to kivy's clock among other things, but easy to rip it out should you need it in a different context. There is also anexample application that can be used to create gesture templates [1]

[0] https://github.com/kivy/kivy/blob/master/kivy/multistroke.py

[1] https://github.com/kivy/kivy/tree/master/examples/demo/multi...