Make streaming optional for the 3D image mappers.

Previously, the default behavior of the 3D image mappers was to stream
the data through the pipeline, meaning that only the part of the input
image that was required to display one (possibly oblique) slice on the
screen was updated.  However, this resulted in the UPDATE_EXTENT changing
whenever a new slice was displayed, triggerring a pipeline update.

The new default behaviour is to set the UPDATE_EXTENT to the WHOLE_EXTENT,
so that the whole extent is updated on the first render, but no pipeline
execution occurs on subsequent renders (e.g. while slicing through the data)
unless the pipeline is modified.

The StreamingOn() method can be used to revert to the old behavior.

Change-Id: I76b31a2ae4b329885d755c2947b62f9a9474b88a
Fixed bug in vtkExecutive::CopyDefaultInformation.

vtkExecutive::CopyDefaultInformation was not copying information
when outputPort was set to -1, which happens when someone calls
update on the algorithm directly. This is in contrast to the
behavior of subclasses, which assume that the request come from
port 0. Changed the code to match this behavior.

Change-Id: I51366fc6c540765b42ccf8cf5814b1c22535ee3f
Merge topic 'copydefaultinfo-bug' into master

24211a1f Fixed bug in vtkExecutive::CopyDefaultInformation.
Merge topic 'image-mapper-streaming' into master

5e2432fb Make streaming optional for the 3D image mappers.
Merge branch 'master' of https://github.com/Kitware/VTK