* Remove general (full) keyboard in layout component
* Implement French keyboard component

* When elements receive the focusin event, their status is changed to
`TOUCHED`
* Replace `this.form.valueChanges` subscription with
`this.unitStateService.unitStateElementCodeChanged` subscription

* Take over tasks of `UnitStateComponent`
* Manage property `unitStateElementCode`
* Removing the passing of the property `unitStateElementCode` by
the components

Console logging is disabled in production mode by overriding the
function in `main.ts`

* Implement as draggable overlay
* Keyboard can be configured as 'mini' or 'full'

* Value and status of all elements are saved
* Move some Methods and Properties from FormService to UnitStateService

* `UnitState.dataparts` has property `elementCodes` property, which
stores status, value and id for FormElement
* When building a unit, the stored value is assigned to the element
when it is initiated
* Removed `UnitState.dataparts.pages`
* Removed methods initPages and addStoredValues

* Rename service to `KeyboardService`
* Replace the two fixed rows for upper and lower case letters
of the keyboard with a general row array
* Rename css classes, variables and methods

* After deleting validation component, element component is no
longer needed and is deleted
* Element overlay takes over the methods of element component

* Delete validation message component
* Use instead `mat-error` inside element components to take advantage
 of `mat-input-field`
* Add get validators method to each form element component
* Display validation messages via `error-transform` pipe

Accidental closing of the keyboard can happen when the user clicks on
the board under the keys

* Bugfix for units without always visible page
* Bugfix for aspect ratio over 50%
* Integration of keyboard

* Fix scrollbar bug
* Remove using of timeout method
* Add Material fonts

Because the always visible page is now positioned at the first place of
the unit definition.

* Remove unnecessary styles
* Refactor case distinctions
* Improve styles of some elements

Refactor styles for elements and element overlays to achieve stretching
of dynamic sections when text areas are resized

Break up the code into smaller methods

* Increase height for textarea and textfield after adding new material
styles
* Remove position for validations