ENH: Update ITKv4 project to integrate BSpline registration improvements.

Thanks to "Andras Lasso <lasso@queensu.ca>" for testing.

From Andras:

"I’ve done some tests and it seems that with the new ITK version
computation time of BSpline registration is significantly decreased
(by a factor of about 1.5-2x), while the computed transforms look
the same.

[...]

MR brain tumor, rigid, 0.01
Nightly: 9 sec
ITK-c768e9b: 8 sec

MR brain tumor, rigid+bspline, 0.01
Nightly: 106 sec
ITK-c768e9b: 49 sec

Dental surgery CBCT, rigid, 0.002
Nightly: 14 sec
ITK-c768e9b: 15 sec

Dental surgery CBCT, rigid, 0.01
Nightly: 66 sec
ITK-c768e9b: 57 sec

Dental surgery CBCT, rigid+bspline, 0.002
Nightly: 76 sec
ITK-c768e9b: 55 sec

Dental surgery CBCT, rigid+bspline, 0.01
Nightly: 1200+ sec (could not wait for it to finish)
ITK-c768e9b: 623 sec
"

// ----------
$ git shortlog 7c3a15eb..c768e9b87c --no-merges
Arnaud Gelas (2):
BUG: fix gdcm version in GDCMImageIO.
COMP: missing cast when calling gdcm::DataElement::SetByteValue

Girish Mallya (1):
BUG: Tests added for BinaryImageToLabelMapFilter for single-row images.

Hans Johnson (9):
PERF: Revert Remove large foot print of PDF derivatives.
STYLE: Test against almost equal for floating point values
STYLE: Non-exact floating point testing
PERF: Distribute initialization per thread buffers
ENH: Remove unnecessary mutable qualifier.
STYLE: Remove comment with no meaning.
ENH: Moved accumlator logic to main MI class
ENH: Allow staggering of accumulations per thread.
PERF: Zero reset thread buffers during finalize

Matthew McCormick (6):
STYLE: Improve style in BinaryImageToLabelMapFilter.
BUG: Fix BinaryImageToLabelMapFilter on 1D image.
ENH: Improve precision of the joint PDF sum
BUG: Fix BinShrinkImageFilter for different input/output image types.
COMP: Fix transform type for ITKv3/IterativeClosestPoint2.
COMP: Add missing wrapping for TransformIOBaseTemplate.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23709 3bd1e089-480b-0410-8dfb-8563597acbee