Merge branch 'master' into unittests

Former-commit-id: fa2b81c47b593e9889212919b189bae25a047132

tutorial/cmake/FindGLEW.cmake

@@ -32,7 +32,7 @@ if(GLEW_FOUND)
   set(GLEW_SOURCES ${GLEW_INCLUDE_DIR}/../src/glew.c)
   message(STATUS "Found GLEW: ${GLEW_INCLUDE_DIR}")
 else(GLEW_FOUND)
-  message("could NOT find glew")
+  message(WARNING "could NOT find glew")
 endif(GLEW_FOUND)
 
 MARK_AS_ADVANCED(GLEW_INCLUDE_DIR)