Replace find_package(PythonInterp) with find_package(Python) to be able to pinpoint Python root.

--- Modules/ThirdParty/GoogleTest/src/itkgoogletest/googletest/cmake/internal_utils.cmake.orig
+++ Modules/ThirdParty/GoogleTest/src/itkgoogletest/googletest/cmake/internal_utils.cmake
@@ -215,7 +215,9 @@
 endfunction()
 
 # Sets PYTHONINTERP_FOUND and PYTHON_EXECUTABLE.
-find_package(PythonInterp)
+find_package(Python COMPONENTS Interpreter REQUIRED)
+set(PYTHON_EXECUTABLE "${Python_EXECUTABLE}")
+set(PYTHONINTERP_FOUND "${Python_Interpreter_FOUND}")
 
 # cxx_test_with_flags(name cxx_flags libs srcs...)
 #



--- CMake/ITKModuleHeaderTest.cmake.orig
+++ CMake/ITKModuleHeaderTest.cmake
@@ -6,7 +6,8 @@
 
 # This does not force the developer to install python to be able to build ITK.
 # The tests will simply not be run if python is unavailable.
-find_package(PythonInterp)
+find_package(Python COMPONENTS Interpreter REQUIRED)
+set(PYTHON_EXECUTABLE "${Python_EXECUTABLE}")
 
 # Improve performance of MSVC GUI, by reducing number of header tests.
 set( MAXIMUM_NUMBER_OF_HEADERS_default 35 )
@@ -30,7 +31,6 @@
   if( NOT ${_name}_THIRD_PARTY
       AND EXISTS ${${_name}_SOURCE_DIR}/include
       AND PYTHON_EXECUTABLE
-      AND NOT (PYTHON_VERSION_STRING VERSION_LESS 2.6)
       AND NOT (${_name} STREQUAL ITKTestKernel)
       AND NOT (CMAKE_GENERATOR MATCHES "^Visual Studio 10.*"))
 

--- CMake/ITKModuleDoxygen.cmake.orig
+++ CMake/ITKModuleDoxygen.cmake
@@ -6,7 +6,8 @@
 # python is needed to verify the presence of the module name in the doxygen header
 # Don't require it to not force the developers to install python to be able to build
 # ITK. The tests will simply not be run if python is not available.
-find_package(PythonInterp)
+find_package(Python COMPONENTS Interpreter REQUIRED)
+set(PYTHON_EXECUTABLE "${Python_EXECUTABLE}")
 
 macro( itk_module_doxygen _name )
 

--- Wrapping/Generators/Python/CMakeLists.txt.orig
+++ Wrapping/Generators/Python/CMakeLists.txt
@@ -1,18 +1,7 @@
 ###############################################################################
 # configure python (find PythonInterp first, as of cmake 3.1)
-find_package(PythonInterp)
-find_package(ITKPythonLibs)
-
-# require at least python 2.6
-if(PYTHON_VERSION_STRING VERSION_LESS 2.6)
-  message(WARNING "Python version less than 2.6: \"${PYTHON_VERSION_STRING}\".")
-endif()
-
-# check for version mismatch.
-if(PYTHONLIBS_FOUND AND PYTHONINTERP_FOUND
-    AND NOT(PYTHON_VERSION_STRING VERSION_EQUAL PYTHONLIBS_VERSION_STRING))
-  message(WARNING "Python executable (\"${PYTHON_VERSION_STRING}\") and library (\"${PYTHONLIBS_VERSION_STRING}\") version mismatch.")
-endif()
+find_package(Python COMPONENTS Interpreter REQUIRED)
+set(PYTHON_EXECUTABLE "${Python_EXECUTABLE}")
 
 if(NOT EXTERNAL_WRAP_ITK_PROJECT)
   CMAKE_DEPENDENT_OPTION(ITK_WRAP_PYTHON_LEGACY "Build Legacy Python support." ON


--- Wrapping/Generators/SwigInterface/CMakeLists.txt.orig
+++ Wrapping/Generators/SwigInterface/CMakeLists.txt
@@ -8,7 +8,9 @@
 
 ###############################################################################
 # Find python
-find_package(PythonInterp REQUIRED)
+find_package(Python COMPONENTS Interpreter REQUIRED)
+set(PYTHONINTERP_FOUND "${Python_Interpreter_FOUND}")
+set(PYTHON_EXECUTABLE "${Python_EXECUTABLE}")
 
 ###############################################################################
 # Build swig