Migrate to Typescript

[heberleh]

The code can be slowly migrated from branch dev to Typescript.

In this text, you find a guide with code:
https://medium.com/swlh/convert-your-javascript-react-app-to-typescript-the-easy-guide-631592dc1876

Please use Webpack since we want to be flexible with the settings, that is, don't use create-react-app.

This issue is a piece towards issue #5

[heberleh]

In the dev branch, I added an interactivenn folder with a basic idea of the new structure of the project in Typescript with React and npm using create-react-app.