The code is on github https://github.com/rgsouthall/math_mesh and bug reports can be made on the issues page there https://github.com/rgsouthall/math_mesh/issues. The zip file of the github master branch https://github.com/rgsouthall/math_mesh/archive/master.zip can be installed directly in Blender by using the 'Install' button in the add-on preferences window. Otherwise move the folder within the zip file to the directory where your system keeps Blender add-ons. Bear in mind that the Blender 2.8 Python API is still evolving and may break this add-on in future.
Once the add-on is activated, and you have exactly two vertices selected in edit mode, the Math Mesh operation can be started with the alt-shift-m keyboard shortcut. Brief tutorial video is linked below. One thing I forgot to mention in the video is that there is the option to align the curve plane with the viewport view direction. Otherwise I think it covers just about everything.