Fix MetaModels/core/issues/589 - wizard and xlabel got mixed up.
Refactor wizard generating into small subroutines.
Refactor option retrieval into own subroutine.
Rename method parseCallback() to parseCallbackPropagated() to phase out propagator.
Vugfix: extend the wizard instead of overwriting it.
Bugfix: extend the onclick property instead of overwriting it.
Drop unused class AbstractStaticCallbackListener.
Allow callback listeners to have restrictions to omit the neccessarity of propagating.
Introduce AbstractReturningPropertyCallbackListener and unit test.
Refactor model property callbacks to extend AbstractReturningPropertyCallbackListener.
Make CallbackListeners aware of restrictions.
Move check of container name into event handler.