ENH: Update ITKv4 version to current release branch (7c3a15e-2014-09-03)

$ git shortlog 372991d..7c3a15ebc --no-merges
Bradley Lowekamp (2):
BUG: Use METER of sCAL scale unit
BUG: Use PNG_SCALE_METER for PNG sCAL unit

Christopher Mullins (1):
COMP: Allows latex to compile for ITKSoftwareGuide

KWSys Robot (2):
KWSys 2014-07-18 (65b36ede)
KWSys 2014-08-04 (e787837a)

Matthew McCormick (9):
BUG: Fix alpha assignment for RGBA TIFF.
BUG: Improve thread-safety and performance of PCAShapeSignedDistanceFunction.
DOC: itk::statistics -> itk::Statistics.
DOC: Remove duplicate text in LaplacianRecursiveGaussian example.
DOC: Fix Software Guide page overruns in IterativeClosestPoint{1,2}.cxx.
BUG: TransformFileReader does not clear its TransformList.
BUG: Prevent dangling pointer in HDF5TransformIO.
COMP: Fix missing prefix in ITKv3ImageRegistration20Test.
BUG: Do not return SmartPointers in TimeVaryingVelocityFieldTransform

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23664 3bd1e089-480b-0410-8dfb-8563597acbee