Simd optimized implementation that uses histogram addition rule. Inspired by "Median Filtering in Constant Time" from Simon Perreault and Patrick Hebert.
Sometimes time output shows something like 18446744073708594056. Don't be scared it means that a new second has started while the program was running resulting in an overflow when the time difference was computed.
Running time on Core i7 930:
940x640 leonid.jpg image 41ms
640x480 test.jpg image 20ms
