Bug fix: fixed a pretty devastating bug in the 'Dao.Struct.atAddress' function by creating a new function 'Dao.Tree.alterNodeWithM' in the "Dao.Tree" module to do all the work for it. Since so many of the functions in the "Dao.Struct" and "Dao.Object.Struct" modules depended on 'Dao.Struct.atAddress' (mostly via the 'Dao.Struct.with' function that made direct use of 'Dao.Struct.atAddress'), none of the instantiations into 'Dao.Struct.Structured' were working properly. But now this has been fixed.