C++: Add tracer()'s result type
Move global variable objects to local
Rename R() to rnd()
Rename S() to sampler()
C++: Use <iostream> instead of <stdio.h>
C++: Add stopwatch
C++: Remove empty column in the art
C++: Add 'f' suffix for floating point values
C++: Add 'megapixels' command line switch
C++: Modify view & scene params the same as Go's

 * Add clamp funciton for float to unsigned char conversion.
C++: Fix 'R' in art
C++: Implement fixed output to "render.ppm"
Merge pull request #18 from t-mat/cpp-go-follow

C++: Reflect recent gorays changes