Complete move to Typescript

[nirga]

Our project started as a Javascript project and is gradually moving to Typescript.

• Complete update of all .js files to .ts.
• Fix all outstanding ESLint issues.

[arimus]

Just a note that issue #81 which I closed is related to this issue.

[nirga]

Thanks @arimus! Are you willing to submit your code as a PR?

[arimus]

I submitted a PR to share my code, but I have not extensively tested. I had trouble testing / setting up this project even after the successful import, but the commit shows how I was able to get a build that moves more to TS and properly works in a commonjs targeted application.