sw_engine texmap: introduced texture mapping polygon drawing.

sw_engine texmap: introduced texture mapping polygon drawing.

Introduced the texture-mapping algorithm for the image-scaler.
With this approach, we can support any arbitrary forms of the transformed shapes
while appling the scale factors - x/y separately.

Also this is more efficient when the transformed image is far from the rectangular form
because our current normal image rasterizer based on the given drawing region whereas
our new approach is span-based.

Thus, we applied this mechanism only for the transformed images.