I just commit the latest changes to pointwise class. Krzysztof Kosinski made a review and i update the changes today. The pointwise and derived class are for store data about ?nodes/curves.Also the branch have a reimplementation of Fillet/Chamfer branch using it. The new Fillet/Chamfer retain all features than the previous one plus now show knots in both sides, optionaly of course.
You can try the branch here: https://code.launchpad.net/~inkscape.dev/inkscape/pointwise