Feature: CLI or NPM package

[AlexxNB]

Would be cool to have a tool for building project in the CI/CD pipeline. For example I have a project https://github.com/AlexxNB/overpass-font-cyrillic . I've copy Glyphr core functions into the scripts directory and it is build my Glyphr's project and generate font files for releases automaticly.

So my proposal to made official tool based on Glyphr core code which will do same things in command line interface or/and as a node library.