Refactor to use default exports

[remojansen]

Many modules have only one export but it is not set as default:

export { Kernel };

So we need to repeat { and } in many places:

import { Kernel } from "./kernel/kernel";

If we used default exports:

export default Kernel ;

We would be able to import as follows:

import Kernel from "./kernel/kernel";

The entire code base is full of this problem and needs to be refactored.

[remojansen]

Done 08909b3