Fixed and added to the vtkAlgorithm's update extent API.
Fixed: SetUpdateExtent() and its ilk were setting the update extent on the input. Fixed it to be on the output. This is more consistent with the executive API. Also updated other code accordingly. Change-Id: Iac92df21b8fa8dbeb58e4e27c5ffc796fadc4eaa Added: API to get update extent from the output.