ENH: Update ITK to include latest backport to ITK release branche

It includes the following additional changes:

Bradley Lowekamp (3):
BUG: Avoid potential exception in itk::Object::UnRegister
BUG: Avoid null deference in PrintSelf with default construction
BUG: Use const pointer in Set method for constant ReferenceImage ivar

Davis Vigneault (2):
DOC: Expanded Canny Edge Detection Example
COMP: Warnings in FFTW Classes when compiling with c++11

Eugene Prilepin (1):
BUG: Fix a template name formation in python wrappings

Matthew McCormick (3):
COMP: Remove unused argument in ConditionVariableNoThreads.
DOC: Correct spelling of Continuous.
STYLE: Use prefix increment operator in ImageBase.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@24657 3bd1e089-480b-0410-8dfb-8563597acbee