A node of an execution tree representing the control flow of a program.
FIXME: the copy method creates insane trees (I do currently no understand
what ITNodes are, but most probably the copy method brings ETNodes and
ITNodes out of sync), up to now I am not sure which behaviour of copy has
been wanted. This bug applies to all subclasses as well.
creates a shallow copy of this node and attaches it to node p
FIXME: FIX this method as it creates not well linked trees Problems: 1)
the children of this node are not linked to their new parent -->
malformed tree 2) the children are not copied themselves and linking
would destroy the old tree