impl/use 2D accel funcs: rect copy, rect fill

[dzavalishin]

struct drv_video_screen_t has

    // Screen to screen copy
    void 	(*copy) (int src_xpos, int src_ypos, int dst_xpos, int dst_ypos, int xsize, int ysize );

    // Screen rect clear
    void 	(*clear) (int xpos, int ypos, int xsize, int ysize );

[dzavalishin]

Use copy in move_xy