This is done according to the Angular best practices and minimizes
namespace collisions when using other packages which might use the same
selectors.

Technically the selectors are not even becessary since we use an Angular
component factory to create element components but it is still useful
for the DOM element naming, for debugging purposes for example.

Now manages it's width and height itself.

Also has some new properties:
- verticalOrientation should be self-explanatory
- dynamicWidth allows the user to set a width manually. The buttons on 
the element automatically stretch to meet the set width (or height).

- Explicitly set the value of the form control of CompoundChildren,
because they are not yet fully registered in the onInit phase.
- Use ChangeDetectorRef to prevent
ExpressionChangedAfterItHasBeenCheckedError

Now correctly sets the chosen background color and additionally sets 
another (configurable) color to the selected value.

This is meant solely as a cloze child as a representation of a radio 
button functionality.