Fix the octave crash under Windows but does not solve totally the problem (which might be related to incompatible iterator when clearing the remaining collection of btk::MEXObjectHandle pointers).
[UPD] Introduction of the NullPtr class and static Null method for all classes deriving of the class btk::DataObject. This should simplify the syntax to test the nullity of a shared pointer without to know the exact API behind the macro btkSharedPtr (i.e. for the class (boost|std)::[tr1::]shared_ptr).
Modification of the syntax for some internal conditions to use adapted operators to test the nullity of shared pointers (i.e. operator!, operator!=, and Null).