added drag and drop support between observer

...motionstudio/gef/editor/action/BMotionObserverWizard.java

...rc/de/bmotionstudio/gef/editor/action/ObserverAction.java

...tor/observer/wizard/WizardObserverCSwitchCoordinates.java

...ef/editor/observer/wizard/WizardObserverDragListener.java

...ef/editor/observer/wizard/WizardObserverDropListener.java

...rver/wizard/WizardObserverListenOperationByPredicate.java

...ef/editor/observer/wizard/WizardObserverSetAttribute.java

...itor/observer/wizard/WizardObserverSwitchCoordinates.java

...gef/editor/observer/wizard/WizardObserverSwitchImage.java

.../de/bmotionstudio/gef/editor/util/WizardObserverUtil.java