The namespace shall also be used for testing the rendering of
`Container`s and `Element`s (including the `Scrollable` element).
The testing renderer currently is a striped down version of the double
buffered render without the secondary buffer and the flushing to stdout.
The internal `Cell` slice (the *screen*) is used for equality checks.
The testing namespace shall provide a way to describe the expected
`Cell` slices that should be validated against.
However this is only working for the same size as the parent container
(i.e. same `Size`). The `.resize` event for the `Container` of the
scrollable element needs to be the necessary and/or required size for
the contents (regardless of the screen viewport).
Remove examples, add description for design goals in README.md and
apply re-names and naming changes accordingly for the project structure.
Implement a flat hierachry, as the library shall remain pretty simple.
