Hint and autostart functionality of videos and audios is initialized
only after dependencies to other audios and videos have been resolved.
This prevents the hint of an audio and video from starting, although
the audio is not yet enabled.

The control bar is shown only when at least one control is selected
in the editor.

The issue here is the alignment if dropLists and text fields. They are 
supposed to be exactly in line with the text which is very complicated 
with Material components, which are heavily nested and contain several 
sub-elements which need to be changed - removing margins, paddings and 
other position related styles.

- Don't use height 100%. The image is not centered but positioned
in the upper left corner

Now scales, taking up all available space.

No unused space around images and image an text below each each other.

This reverts commit b5d3b810.

The old behaviour with non-scaling images is wanted here. Will improve in subsequent commit.

Extend the parsing to inludes h-Elements.

Setting on type button avoids that click events are evaluated from
the surrounding form

Before the parent elements (span, div...) were catching the drop event 
which is not intended.

Also all elements now take the parentForm as input. Allowing it to use 
them with template binding and not only setting the value directly (in 
the controller).

Child elements need some special CSS, for example to prevent taking up 
more space than needed.
This is only for text field and drop list, which are the relevant sub 
elements for now.

The problem that was to be solved is that buttons within a form always 
cause form validation for all form elements. Which is not wanted here.
The better solution than preventing all event is to simply declare the 
button type. As button without any type are treated as submit buttons.

A new variable is introduced for CompoundComponents: 
"allowClickThrough". With this set components can set their children and 
overlays to allow clicking on child elements or not. In the editor this 
is not wanted as the elements internal structure is different and the 
resulting event target can not be reliably styled. There we need the 
(span) overlay.
In the player though elements should be clickable as usual. The player 
can completely ignore this setting as it is on true (allowing clicking) 
by default.

- Remove fallback of TranslationService to allow empty error messages
  that can still cause red borders
- Remove the case distinction for checkboxes, since the requiredTrue
  validator also sends required as errorKey and a special fallback text
  is no longer used

They both have an element model and makes sense that a compound 
component is also a 'normal' component.

SHould now always correctly line up with the text even on different line 
heights.

Similar to a text element but parses the text on change an replaces 
markers with actual elements.
The text is then displayed inline with the elements.

This allows to use them in template bindings. Used in compound elements.

Improve general structure. Image situation still bad.

- Images now scale up and down depending on the available space.
- The new property controls the first (column) size parameter for the 
grid. The others are fixed at 1. Decimal values are allowed for 
fine-tuned control.
This prop is passed on to the child likert-row component. It uses the 
same grid and needs this info for proper alignment with the column 
headers.
- Remove unnecessary div in likert

- List items only have a margin between then but no longer on the 
outside.
- Remove unused background color. This is set dynamically in the 
template.

In ControlBarComponent the property project replaces the property
isAspectPlayer. It ensures that delays are used only in the player
and hints are always visible in the editor.

The magnifier is always visible in the editor

Required to query the elementModels of all instances of this class.