Error Handling / Warning for changed model

[michael-burk]

Right now if we change the object, that is connected to the Binder, this causes Null-Pointer errors in Binder or Timeline.

Ideally theses errors would be catched and the Binder would output a warning, that the model has changed, or that the bound object doesn't correspond th the Timeline-Model. This is to avoid frequent crashes when patching.

[michael-burk]

See also #49