Fixed wrongful logic for ExtractOnlyBoundaryCells in vtkExtractGeometry.

The ExtractOnlyBoundaryCells is not working properly due to some logic
errors in deciding when to extract cells if both ExtractBoundaryCells
and ExtractOnlyBoundaryCells are on. Fixed it.

Change-Id: I0574c672507ca610b1e77272d12f4e8acc3efa0c
BUG #12994. vtkXMLMultiBlockDataWriter not writing names for leaf nodes.

vtkXMLMultiBlockDataWriter was not saving out names for leaf nodes the the
mulitblock dataset. Names were only being saved for non-leaf nodes. Fixed that.

Change-Id: If68a32d64ad5eab2c5f107a236cba6dfecfe125d
Merge branch '12994-xmlmultiblockwriter-improvements-rel' into release
Make some color methods consistent.

In order to use functions like SetTableValue(2, "Blue") in a lookup table
  or other SetColors in derived classes in the same manner,
  these methods should be virtual.
This commit just makes the relevant Set methods virtual.
In the case of vtkProperty, the definition of SetColor(double a[3]) has
  been moved into vtkProperty.cxx, the rationale is that, in VTK classes,
  definitions occur in the implementation file not the header file.

Change-Id: I89fee8eb4902e0847114b068374c3bff0bf10b9d
Merge branch 'Virtualize_Color_Methods-rel' into release

Change-Id: I77e1b3b31a1392fb2bb2031f1ec77cbf8234cc9e