AddProcessObject::ToString method to print active process object

Change-Id: I7b3de7f699adb3d12a28a3d004ba029a44dfd10a
ENH: Printing more ivars in process object class

Change-Id: I40ec75769deb111c9c0644c49da946583b612078
Print super classes for Image IO classes

Change-Id: Icebe4c4ca6acd09d852d4371ee57dc6e4519d07a
Adding printing of process object parent to filters

Change-Id: Ie33a41927581d75cbd25c721c8c33e4d5fb438bd
Merge topic 'SIMPLEITK-483_PrintParentObject' into next

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