[Progress]Aligned Memory allocation

For now, I use _mm_load_ps to load the data into __m128 datatype. Somehow I don't face the problem that needs to use _mm_malloc() to specify 16-bit aligned memory allocation, but I haven't done yet, so maybe there's some problem not yet found.

This time I do overload the operator and save lots of redundancy code which makes the code more understandable (even though in practice, it's not faster.)

Hope I can finish the BVH with SSE tomorrow.