C++: Rename v4f/v8f to Float32x4/Float32x8 respectively
C++: Use delegating constructors
C++: Merge SSE and AVX codes in tracer() and Scene
C++: Rename vector4 and vector8 to Float32x4x3 and Float32x4x8 respectively
C++: Move CommandLineParser to ArgumentParser.hpp

 - Almost the same as javaray's.
C++: Move Result to Result.hpp
C++: Add Pixel and Image
C++: Add imageSize to ArgumentParser

 - NOTE width and height are more natural argument
C++: Split SSE/AVX classes to independent header files
C++: Improve GCC compatibility
C++: Add generic vectorization template