Although the nitty gritty of the maths is largely unchanged, everything else has been completely rewritten using Polymer 1.4, and various features and syntax from ES6. Previously the code could only be described as a mess (though highly performant). Now it is both highly performant and pretty tidy, on the whole.
A few features have been lost since the previous version, but they will soon be reinstated. There are also likely to be some bugs to be ironed out.
Once all that is sorted v1.0 will be ready.