Added Type Declarations for TypeScript Support and Better IntelliSense

[JeffMII]

With the help of @joelyjoel 's issue, I added type declarations to the project. The majority of the work was done by @joelyjoel . It was just a matter of updating it to match the current version of the project and adding a couple of small improvements to make the IntelliSense work great with the Definition object that's returned from the lookup method.