Integrate typescript types

[yannbriancon]

Currently, typescript types are given and maintained through DefinitelyTyped (code, npm).

I saw some missing types like the new epsilons.
Would you consider adding the types to the repo and maintaining them here to avoid unsynchronised types?

[HarryStevens]

Yes, I really need to do this. I also got this suggestion in a pull request.

I am not a TypeScript user myself. Can you recommend any good tutorials so I understand what I'd need to do to add this?