Document or find replacement for Ngrams.js

[akohlbre]

• If possible, find existing library to replace this file
• If not, add documentation to the existing file

[jonathanmayer]

Per @benjaminhkaiser, this code is from the simplengrams package.

https://www.npmjs.com/package/simplengrams https://github.com/phughesmcr/SimpleNGrams

Looks like version 2.0.x; there are breaking API changes in 3.x.

As a first step, we should replace Ngrams.js with an NPM package dependency. We should eventually migrate to the current version of a more actively maintained toolkit, like natural.

https://www.npmjs.com/package/natural https://github.com/NaturalNode/natural/blob/master/lib/natural/classifiers/classifier.js

[jonathanmayer]

Closing here, reopening on the web-science repo.