Element margins and grid sizes now have a measure unit attached. The 
translation logic to merge unit and value are done via Pipe.

Media elements needs time to load and change the dimensions of the page

#441

Replace the assignment of the ElementComponent with the assignment of
a ElementComponent that will work in future versions of Angular

Displaying a message is task of the host
#398

- Prepare usage in editor
- Remove test from ScrollPagePipe, because the call to "new Page" expected
  the initialization of GeometryComponent

- Remove css margins of floating keypad

- A floating keypad is generated inside a div with the class
  'cdk-overlay-pane'. Now the position of this div is updated when
  dragging the keypad.