To now, each property hat an _invalidationLevel field that was evaluated by processors when the property had changed in order to determine what has to be done. However, since properties could also be owned by other classes, this design was semantically misleading.
Therefore, it was removed with this commit and replaced by the invalidation map of each processor. Now, this per-processor mapping of property -> invalidation level is managed by the processor itself. Furthermore, the invalidation level is no longer setup during property creation but during AbstractProcessor::addProperty(), which also makes much more sense.

ATTENTION: Due to these intrusive API changes, the code of all processors and other classes handling properties needs to be changed. As a reminder, the implementation of addProperty() also now takes a reference instead of a pointer, so that old code does no longer compile.

refs #542