Dataflow extension for FilterDesigner

[w9n]

This is a more powerful implementation of the FilterDesigner elements using DataflowEx.

It adds a viewmodel for a connection and gives each Filterdesigner element n input and output connector of different possible types.

the first inheritance level of these parts are different abstract ViewModel to bind to the view.

The second one is abstract and generic and specifies the type and connectivity of a Connector or Connection.

And the last one is the specfic implementation that handles the Data and Model access.

It logs the amount of elements in the end Element of a Dataflow every two seconds but counts them twice currently.

the example elements like ShaderEffectElement and Multiply might finally use composition over inheritance.

The DataFlow types of an element should be changable in the UI.