Update TypeScript definitions for V1 API

[mattrcarter]

The latest TypeScript definitions available on https://github.com/DefinitelyTyped/DefinitelyTyped are for popper.js v0.4.x. Would you be willing to update the definitions to reflect the breaking changes in the v1 API?

Steps to reproduce the problem

1. Install popper.js latest version (v1.8.4 at time of this issue)
2. Install latest TypeScript definitions from https://github.com/DefinitelyTyped/DefinitelyTyped (for v0.4.x at time of this issue)
3. Add a custom modifier as described here: Popper.js v1 API migration instructions #62

What is the expected behavior?

Custom modifiers would be definable.

What went wrong?

The wrong types for modifiers in the TS definitions prevent compilation of TypeScript code.

Any other comments?

If you'd like help updating the definitions let me know and I'll see what I can do to help out.

[FezVrasta]

I never used TypeScript. The whole API is described in the documentation. I use JSDoc to describe the types so maybe there's a tool to automatically generate them from jsdoc?

[FezVrasta]

I tried https://www.npmjs.com/package/tsd-jsdoc but it throws a lot of warnings because of invalid types like Object Array, HTMLElement, Boolean, String...

[FezVrasta]

I'm going to close this since there's already a PR to update the definitions in the DefinitelyTyped repo.