graphic: add testdata
graphic: update test code
graphic: refactor code, add loadImage(), saveImage()
graphic: add rotate image functions, update testdata, update test code
graphic: add FlipImageHorizontal(), FlipImageVertical()
graphic: rewrite RotateImageLeft() and RotateImageRight(), do not use lib/go-graphic
graphic: add BlurImage(), depends on lib/go-graphic
graphic: rewrite BlurImage(), do not depends on lib/go-graphic