Moves the objects with object ids as specified in the second
parameter from the collection with id source_id
to the collection with the id destination_id.
If the destination id is 0 the objects will
be unlinked from the source collection. If this is the last instance
of that object it will be deleted. If you want to delete all instances
at once, use hw_deleteobject().
The value returned is the number of moved objects.
See also hw_cp(), and hw_deleteobject().