- Important for vertically positioned drop lists
- Analogous to the calculation of the height

- Replace pixel calculation with percentage values
- Use of only two modes: full fill or line

#343

i.e. something has been clicked.
Since the value is not used on the player, we also need to check the 
FormControl value.

#335

- This makes the behavior identical to real form elements
- To trigger the focusout event, the HTML element needs
the tabindex attribute

simple dropdown lists need a minimum height so they don't collapse
if they don't contain any element

Using disabled cause conflicts with reactive form in player

- Add "isOlderThan" method to the "SanitizationService" to distinguish
old ToggleButtons with the property "option" from new ones
- Use SanitizationService.isUnitDefinitionOutdated in Player to set
the unitDefinitionVersion (should be modified!)

Use the same settings as in simple drop list

ViewEncapsulation.None is required for overriding tooltip

DragNDropValueObject no longer has the stringValue property
but a TextLabel with text

One as a general label above the table and one for the first column 
heading.

Since this is no proper InputElement separate properties panel inputs 
are used.

#272

To be the same as with Material inputs.

#319

So TipTap does not moan about empty document.
Put placeholder text in the cloze document instead of the component 
template.

Also add it to the likert row dialog.

#112

Also refactor properties panel and ToggleButton class logic for striking 
values. This now relies more on CSS classes provided by Material instead 
of doing finetuned logic my ourselves. This also allows showing the 
correct preview in the editor.

#287

Turns out the space within the template code are doing this.

#270

Italics indicate that this is not a proper text.

This is needed in on drop logic to set the new value.

- remove prefix 'on'
- split methods

This way elements can handle their logic themselves without having to
rely on outside utility classes.

Also restructure files in common in a more logical way.