- Prevent input of 'Dead' keys

This reverts commit 7a697cd9.

- Toggling of keyboard and keypad are now async
- Keyboard and keypad animations are disabled for a short period of time

- Input field manipulation moves from service methods to new
  TextInputGroupDirective

Making element components unclickable is now applied to all child 
elements. This is necessary because some Material-components have child 
elements with specific pointer-events settings, which makes it possbile 
to interact
with them even though the parent is not clickable.

It is also now set via class on a parent element instead of the 
component itself.

#524

(which is the height of a single item)

#525

This makes the controls fit better into the fieldset box.

The color buttons now use outline instead of background-color for 
showing the selected color.

Also some alignment improvement and a hover marker for the select 
button.

#553

- and AnswerSchemeValue with VariableValue

- Remove unused imports

Windows convertibles were not recognized as mobile devices by this check

#599

- Now every element can overwrite 'getAnswerScheme' of 'UIElement'