Allow Text3D to use TTFLoader

[mz8i]

Describe the feature you'd like:

three-stdlib provides a TTFLoader that automatically does the same type of conversion that happens when using the Facetype.js website. Text3D should support both loaders, depending on the content-type returned from the fetched URL. This way, especially during development where speed of loading is not a concern, developers don't have to manually convert fonts using the Facetype.js website, which slows down experimentation with different fonts / variants etc.

Suggested implementation:

I will submit a PR soon.