Merge topic 'SIMPLEITK-483_PrintParentObject'

fb9191bd Adding printing of process object parent to filters
3475301c Print super classes for Image IO classes
5fa8db6c ENH: Printing more ivars in process object class
43206be7 AddProcessObject::ToString method to print active process object
Merge topic 'SIMPLEITK-543_UpgradeITKTowards4.6'

8c1c4a17 Updating superbuild ITK to include ITKv4 registration revision
Merge branch 'master' into next

Change-Id: I1b452334cc58953b9a4db67f6d14031f08d6cc03