- Improve tests
- Change log level logic
- change default log level

'text-field' and 'drop-list' now need '-simple' suffix.

- Disable explicit any rule, because here the native interface of
'window.console' uses 'any[]'

- default log level is 1 (logs are not displayed,
but info, warn and error)
- uses its own logging module
- add path to logging module in tsconfig

Use private methods
Define all messages as properties

Show accordion with expansion-panels instead of tabs.
This way elements can be grouped logically.

Reloading a UnitDefinition includes loading the current UnitState

This facilitates the testability

- Reduce amount of properties
- Split code in separate methods
- Define some properties as input properties

This eliminates the need to specify the different page types in
AppComponent

Knowledge of the 'document' existence is only a matter of the function 
not the caller.

- Add fieldset and reorder fields
- Add dynamic connectedDropLists menu

Components with bigger scope are put to the component root, canvas, 
props panle and new-element-panel.

Makes more sense logically to pass the cloze element as a whole instead 
of just the document. Knowing about the document is the responsibility 
of the method not the caller.

- Move value input to dropList input group

- Fix DropLists with copyOnDrop to display a placeholder copy of
dragged elements.
The drop preview is hidden on those lists. It still has to be in the DOM
to be the target for the 'falling' animation of the dragged item,
otherwise it flies to the top left corner of the viewport.

This marks the end of the test according to the expect method