HAL: improvements

- added new functions from core module: split, merge, add, sub, mul, div, ...
- added function replacement mechanism
- added example of HAL replacement library

modules/imgproc/src/precomp.hpp

@@ -94,4 +94,6 @@ extern const float icv8x32fSqrTab[];
 #include "_geom.h"
 #include "filterengine.hpp"
 
+#include "opencv2/hal/sse_utils.hpp"
+
 #endif /*__OPENCV_CV_INTERNAL_H_*/