Champ Yen

Results 2 issues of Champ Yen

a preliminary support for Linux/SDL2

the code snippet: scale(x,y,c) = Halide::cast( **(1-s) * (1-t) * input(x_lower, y_lower+1, c) +** s * (1-t) * input(x_lower+1, y_lower, c) + (1-s) * t * input(x_lower, y_lower+1, c) +...