- Add fieldset to make it look nicer.
- Improve image to have fixed size, scale properly and show buttons only 
on hover.
- Improve translations
- Add tooltip to actionparam dropdown: When having selected pageNav it 
shows a tooltip to get across that only valid pages can show up.

#240

This reverts commit d053d03c.

This feature will first be developed properly in a branch.

Cloze documents now use this correctly.

#222

verticalButtonAlignment is the new property for likert rows, which tells 
the actual radio button to either be at the top or in the middle.

This allows showing the contained text in multiple columns.

This can be enabled for TextFields and TextAreas and shows a keyboard
at the bottom of the screen. This does NOT set the field to read-only
which is probably wanted in a situation where the system keyboard is not
to be used. For flexibility purposes it is not implicitly set and needs
to be set manually. The same goes for other input assistance settings,
which should not be used in addition to the keyboard but it is allowed.

The keyboard has an extra switch to additionally show french special
characters.

gridColumnStart: number;
gridColumnEnd: number;
gridRowStart: number;
gridRowEnd: number;

becomes

gridColumn: number;
gridColumnRange: number;
gridRow: number;
gridRowRange: number;

Now uses the implicit grid in auto mode.

Change translation key and meaning from 'typeAreaWidth' to
'sectionWidth'

Remove case distinction when labeling the page's margin width

The width of a page results from the value for the maximum width plus
twice the value for the spacing

Note that autostart of audios and videos does not work for tablets

- 'hideOtherPages' is not supported by verona api
- 'uninterruptible' is already fulfilled by disabling pause and
progress bar

Refactor MathKeyboardComponent to reduce code size

This allows elements in dynamic sections to have fixed dimensions.

Some modifications to property panel logic, to show dimension fields and
proper labels.

Only implmented in dropList and button elements.

This new setting makes child items space around in a row with line 
break.

Images in vertical alignment now always reserve the whole row and don't 
appear next to each other.

Now correctly sets the chosen background color and additionally sets 
another (configurable) color to the selected value.

If the property is set, the video will be scaled as far as its
container (static element or grid) allows, otherwise only up to its
maximum native size.

If the property is set, the image will be scaled as far as its
container (static element or grid) allows, otherwise only up to its
maximum native size.

The interaction can now be turned off without hiding the button.

Min-height should be optional for dynamically positioned elements, as 
you usually don't need it and it causes more problems than it solves. 
Elements with min-height have cause unexpected margins between elements.