Fix crash in vtkFixedSliceHandleRepresentation3D

If BuildRepresentation is being called without a renderer, DisplayToWorld()
was crashing. This was the case in the TestSetGet unit test.
Regression from f8fe12a648f2d08ea095beb093b43029062d256d

Change-Id: Ia9f8dc33a91af66fbda108a1832c242ccf6ebcf2
Added a SeedIds array to the output of stream tracer.

The SeedIds array is a cell array that contains the ids of
input seeds for each polyline in the streamtracer output.
This can be used to identify which streamline came from
which input seed.

Change-Id: If045716a4b7a19d02f26d16d25864b5f7fbb3a38
Merge topic 'fix-vtkfixedsizehandlerepresentation3D-crash' into master

7a2f6bf2 Fix crash in vtkFixedSliceHandleRepresentation3D
Merge topic 'add-streamline-seedids' into master

07b7459d Added a SeedIds array to the output of stream tracer.
Added support for specifying split mode.

When the vtkStreamingDemandDrivenPipeline automatically
partitions a structured request because of CAN_PRODUCE_SUB_EXTENT
being set, it always used vtkExtentTranslator::BLOCK_MODE. I added
support for downstream filters to specify a split mode to be used
as an alternative. This is done by setting the UPDATE_SPLIT_MODE
key in RequestUpdateExtent.

Change-Id: Ie8dc2af898352adeaa261405d483ac619c035021
Merge topic 'split-mode-request' into master

d8bdbb60 Added support for specifying split mode.