Property :: isValidForParent - Is subhandle valid for parent passed

When an application uses dynamical property hierarchies, in which property handle may change, the function can be used in order to check, whether a property handle in the hierarchy is still valid.

The function checks, whether the property handle is a sub-handle of the parent property handle passed to the function. When the property is a valid sub-handle, the function returns the level of subordination, e.g. 1 for directly subordinated properties, 2 for sub sub properties etc. When the property is not a valid sub-handle for the property handle passed in cProperty, the function return 0.