ENH: adding ITK version defines with SITK prefix

Adding SITK_ITK_VERSION_... defines, from CMake variables, to
sitkConfigure.h. In order to define code conditional on ITK versions
we need to have ITK version information available in SimpleITK headers
but we can't include ITK headers, so we have use the CMake variables
to define pre-processor variables in SimpleITK's configuration
header.

Change-Id: Ib1a579693dcf3f6c4d2821c26976248c7430ca96
COMP: Templated ITK Transform API change

The Transform class became templated such
that they now support both float and double
precision numbers natively.  This change
provides a nearly backwards compatible
typedef, but that typedef does not
propogate through the forward declaration
of the class.

// Forward decalaration for pointer
-class TransformBase;
+template< typename TScalar > class TransformBaseTemplate;
+typedef TransformBaseTemplate<double> TransformBase;

Change-Id: Ife10906ec480be313c489bb08cff8ad8ab24ee6b
Merge branch 'FixForITKWithSinglePrecisionTemplate' into release

* FixForITKWithSinglePrecisionTemplate:
  COMP: Templated ITK Transform API change
  ENH: adding ITK version defines with SITK prefix

Change-Id: I0367241a201e0c282ea9b3a4be49acc8e3d894ca