Add TypeScript support

[vahdet]

Add TypeScript support

[OleksandrYehorov]

@vahdet @JamesBrill @types/react-speech-recognition is now available.

[JamesBrill]

Thank you @OleksandrYehorov - that is hugely appreciated. 🙇

[JamesBrill]

Hi @vahdet thanks for the suggestion. I have no experience with TypeScript (though it is of interest to me), so you may be better positioned to contribute a declaration file than me. If you make a PR for this, I can advise on the types and shape of the inputs/outputs.

You probably don't even need to do the whole thing - if you get it started and help me get an idea of how to structure and publish a declaration file, I can probably fill in the missing definitions.

[vahdet]

@JamesBrill Well, yesterday I tinkered with the code indeed. I forked the repo applied my work on a new branch feature/typecript-support. I have some experience with TypeScript, but cannot call myself a master of it. Anyways, I am sending a PR w/ my further explanation on what I've done; and then, improvements can be done on it (see: #52)

I won't be around for a couple of weeks, so I may react slower than today..