3MFLoader fails to load JSZip if imported using `import`

I am using TypeScript and WebPack so there might be some magic transpiling stuff happening which makes import work when added to 3MFLoader.js; thinking of it I think that is some TypeScript magic.

Shouldn’t 3MFLoader.js import/require JSZip if it depends on it? If that is not doable maybe we can make the loader constructor take JSZip as an optional parameter?