add md5 logic to isogrid with colors

// Isogrids is the handler for /isogrids/[a-zA-Z0-9]+/?.

// builds a 10x10 grid with alternate colors based on the string passed in the url.

func Color(w http.ResponseWriter, r *http.Request) {

	if id, err := misc.PermalinkID(r, 2); err != nil {

	if colorId, err := misc.PermalinkID(r, 2); err != nil {

		log.Printf("error when extracting permalink id: %v", err)

	} else {

		if id, err1 := misc.PermalinkString(r, 3); err1 == nil {

			h := md5.New()

			io.WriteString(h, id)

			key := fmt.Sprintf("%x", h.Sum(nil)[:])

			colorMap := tgColors.MapOfColorPatterns()

			bg, err1 := extract.Background(r)

			if err1 != nil {

			bg = colorMap[int(id)][0]

				bg = colorMap[int(colorId)][0]

			}

			fg, err2 := extract.Foreground(r)

			if err2 != nil {

			fg = colorMap[int(id)][1]

				fg = colorMap[int(colorId)][1]

			}

			size := extract.Size(r)

			write.ImageSVG(w)

		draw.IsogridsSkeleton(w, "", bg, fg, size)

			draw.Isogrids(w, key, bg, fg, size)

		} else {

			log.Printf("error when extracting permalink string: %v", err)

		}

	}

}