- 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!)

The equality check compares the reference of the array and not the
values of the array.

Use css grid instead of flex plus calculating margins in template

Using the html property "disabled" results in a warning message in the
player when reactive forms are used at the same time.

Fix import order

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

# Conflicts:
#	projects/common/models/elements/compound-elements/cloze/cloze-child-elements/drop-list-simple.ts
#	projects/common/models/elements/compound-elements/cloze/cloze-child-elements/text-field-simple.ts
#	projects/common/models/elements/compound-elements/cloze/cloze-child-elements/toggle-button.ts
#	projects/common/models/elements/compound-elements/likert/likert-row.ts
#	projects/common/models/elements/element.ts
#	projects/common/models/elements/input-elements/checkbox.ts
#	projects/common/models/elements/input-elements/drop-list.ts
#	projects/common/models/elements/input-elements/dropdown.ts
#	projects/common/models/elements/input-elements/radio-button-group-complex.ts
#	projects/common/models/elements/input-elements/radio-button-group.ts
#	projects/common/models/elements/input-elements/slider.ts
#	projects/common/models/elements/input-elements/spell-correct.ts
#	projects/common/models/elements/input-elements/text-area.ts
#	projects/common/models/elements/input-elements/text-field.ts
#	projects/common/models/elements/text/text.ts
#	projects/common/models/section.ts
#	projects/editor/src/app/services/verona-api.service.ts

This button helps the user to detect if a page has additional,
hidden content

DragAndDropValueObjects are now a sub-interface of TextImageLabel, which 
requires a set imgSrc and imgPosition property. (The reason is that the 
editor needs a way of generating Labels therefore needs the imgSrc set 
to something else but undefined.)