ENH: Update VTK6 to include backported bug fixes and tweaks

$ git shortlog 169b37b..6c6e5d3
Andrew Bauer (1):
Fixing overflow issue that appeared with GCC compilers.

Ben Boeckel (4):
python: fix leaks when setting constants in wrappers
STLWriter: Raise an error for non-triangles
STLReader: Close the file when an error occurs
STLReader: Fix error signaling when reading files

Bill Lorensen (1):
BUG0013829: vtkAssembly::GetBounds adds bounds which are uninitialized

Brad King (1):
Examples: Set required CMake version and policies before project()

Cory Quammen (1):
Added "sticky" axes mode to vtkCubeAxesActor

David C. Lonie (1):
Handle empty array initialization in numpy_support.

David Gobbi (7):
Fix a crash when deleting vtk-python objects.
Fix warning about trailing comma in enum list.
In wrappers, guard against #including dirs.
Fix cell picker for images with negative spacing.
Fix uninitialized array warnings.
Bad null pointer check in vtkBSplineTransform.
Fix bad SetColor/GetColor interaction in vtkProperty.

Jean-Christophe Fillion-Robin (2):
vtkPythonCommand - Add support for additional call data types
vtkPythonCommand - Fix indent and variable names

John Stark (1):
Fix pipeline update issues in vtkImageExport

Julien Finet (2):
Prevent error message when deep copying vtkGridTransform
Change GetInputConnection error message into a debug warning message

Sankhesh Jhaveri (1):
BUG: Border visibility from underlying vtkScalarBar actor

Sean McBride (30):
Fix clang analyzer warning about passing null to strcmp
Fixed clang analyzer warning about passing null to memcpy
Fixed clang analyzer warning about reading uninitialized memory
Fixed clang analyzer waring about a dead store.
Fixed clang analyzer warning about dead store
Fixed clang analyzer warning about dead store.
Fixed clang analyzer warning about dead store.
Fixed clang analyzer warning about dead store.
Fixed clang analyzer warning about dead store.
Fixed clang analyzer warning about 2 dead stores.
Fixed clang analyzer warning about dead store.
Fixed clang analyzer warning about reading past an array.
Fixed several clang analyzer warnings.
Fixed clang analyzer warning about reading uninitialized memory.
Fixed clang analyzer warning about dead store to 'pd'.
Fixed clang analyzer warning about passing null to memcpy.
Fixed clang analyzer warning about dead store to 'index'.
Fixed clang analyzer warning about dead store to 'bestTime'.
Workaround clang analyzer warning by creating temp variable.
Fixed clang analyzer warnings about dead stores.
Misc cleanup of code nearby clang analyzer warnings.
Fixed clang analyzer warnings about dead stores.
Fixed clang analyzer warning about dead store at very end of method.
Fixed clang analyzer warning about dead store to 'itr'.
Fixed clang analyzer warning about dead store to 'cptr'.
Fixed null deref found by clang analyzer
Fixed clang analyzer warnings about dereferences
Suppress clang analyzer warning
Fixed clang analyzer warning about null deref
Fixed clang analyzer warning about reading uninitialized data.

Thomas Vaughan (1):
Set origin and spacing in vtkSurfaceReconstructionFilter. Ref: Mantis 0002826.

Tristan Coulange (1):
BUG: Add a missing include for VS 2013

Utkarsh Ayachit (3):
BUG #14599: Handle double values properly.
Add support for empty strinngs in SetInputArrayToProcess.
BUG #14244: Fix stereo image captures.

Will Schroeder (1):
Fixed bug causing plane to disappear on boundary.

Xabi Riobe (1):
BUG: The method vtkClipPlanesPainter::UpdateBounds must not be implemented.

xabi riobe (2):
Fix numerical precision problem in vtkCellLocator::IntersectWithLine
Add default value for argument

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23548 3bd1e089-480b-0410-8dfb-8563597acbee