added some invalidation tests. fixed doctest failure
added io_graph function to depgraph. not used for anything yet
Merge branch 'hifi' of https://github.com/Kenneth-T-Moore/OpenMDAO-Framework into newdepgraph
fixed problem with calling get with a numpy index of the form [a,b].
Merge branch 'newdepgraph' of github.com:naylor-b/OpenMDAO-Framework into hifi