General changedHandler for AttachedBehaviors

[zewa666]

When you create an AttachedBehavior with multiple properties, this leads to having a lot of different changedHandlers. So it'd be nice if we could come up with a general handler, which gets called no matter what property changes.

Also we should think about the possibility to batch property changes and trigger the callback only once. As an example let's say you wrap Bootstraps Popover and in the handler you'd like to re-initialize the component. So instead doing it for each property change, having them stashed and only executing the function ones would be nice.

Regarding naming I'd propose one of the following:

onChanged
onPropertyChanged
propertiesChanged
anyChanged

the serialization should contain the propertyName as well as the newValue for the prop.

[zewa666]

Ok this one is kinda deprecated and alternatively dynamicProperties solve the same thing as well