Fix cmake findnumpy

- Fix python code that is injected into python interpreter
- Proper error handling => fatal_error to stop cmake run if numpy not found

cmake_support/FindNumpy.cmake

@@ -7,16 +7,15 @@ endif (PYTHON_NUMPY_INCLUDE_DIR)
 
 IF(PYTHON_BINARY)
     EXEC_PROGRAM ("${PYTHON_BINARY}"
-      ARGS "-c 'import numpy; print numpy.get_include()'"
+      ARGS "-c 'import numpy; print(numpy.get_include())'"
       OUTPUT_VARIABLE PYTHON_NUMPY_INCLUDE_DIR
       RETURN_VALUE PYTHON_NUMPY_NOT_FOUND)
-
-    if (PYTHON_NUMPY_INCLUDE_DIR)
+    if (PYTHON_NUMPY_NOT_FOUND)
+      set(PYTHON_NUMPY_FOUND FALSE)
+    else (PYTHON_NUMPY_NOT_FOUND)
       set (PYTHON_NUMPY_FOUND TRUE)
       set (PYTHON_NUMPY_INCLUDE_DIR ${PYTHON_NUMPY_INCLUDE_DIR} CACHE STRING "Numpy include path")
-    else (PYTHON_NUMPY_INCLUDE_DIR)
-      set(PYTHON_NUMPY_FOUND FALSE)
-    endif (PYTHON_NUMPY_INCLUDE_DIR)
+    endif (PYTHON_NUMPY_NOT_FOUND)
 ENDIF(PYTHON_BINARY)
 
 if (PYTHON_NUMPY_FOUND)
@@ -24,9 +23,9 @@ if (PYTHON_NUMPY_FOUND)
     message (STATUS "Numpy headers found")
   endif (NOT PYTHON_NUMPY_FIND_QUIETLY)
 else (PYTHON_NUMPY_FOUND)
-  if (PYTHON_NUMPY_FIND_REQUIRED)
+  if (Numpy_FIND_REQUIRED)
     message (FATAL_ERROR "Numpy headers missing")
-  endif (PYTHON_NUMPY_FIND_REQUIRED)
+  endif (Numpy_FIND_REQUIRED)
 endif (PYTHON_NUMPY_FOUND)
 
-MARK_AS_ADVANCED (PYTHON_NUMPY_INCLUDE_DIR)
\ No newline at end of file
+MARK_AS_ADVANCED (PYTHON_NUMPY_INCLUDE_DIR)