TypeScript type definitions

[corwin-of-amber]

(still working on this branch, just letting you know)

I imported the definitions from DefinitelyTyped and added the missing constructor.
I am working on porting their tests to use tsd, theirs use dtslint which is a huge overkill.

[corwin-of-amber]

BTW I see coffee-script referenced in coffee-script but no .coffee files. Looks like docopt is written in CoffeeScript but is already compiled to JS in the npm package, so perhaps this dep can be removed?

[corwin-of-amber]

I added the test files and they look ok, to run them all that needs to be done is npx tsd. Should I add this command to the npm run test script?