RFC: use TypeScript

[calvinf]

Thank you for creating this library. I'm a big fan of ABS's Bible API and this resource makes using the latest version of their API very easy.

Summary of this "RFC" (Request for Comment)

I propose to update the code to use TypeScript either directly or by producing a module declaration. Either option will make it easier to integrate with TypeScript code bases.

Producing a TypeScript version of this library should be relatively straight forward as for the most part it will involve updating the APIs to mark the expected input and output formats of the functions provided to users.

Contribute
I'm willing to contribute to making the change including setting up TypeScript, its config, and outputting in the relevant formats for consumers of the module.

[olawalejarvis]

Please, go ahead and make the changes