Don't round calculation of rowHeight and columnWidth in the drawGrid function....

Don't round calculation of rowHeight and columnWidth in the drawGrid function. If you want to plot points on the drawn grid, rounding these figures will lead to inaccuracies.
Signed-off-by: Dmitry Baranovskiy <dmitry.baranovskiy@gmail.com>

raphael.js

@@ -1375,12 +1375,14 @@ var Raphael = (function (type) {
             C.drawGrid = function (x, y, w, h, wv, hv, color) {
                 color = color || "#000";
                 var p = this.path({stroke: color, "stroke-width": 1})
-                        .moveTo(x, y).lineTo(x + w, y).lineTo(x + w, y + h).lineTo(x, y + h).lineTo(x, y);
+                        .moveTo(x, y).lineTo(x + w, y).lineTo(x + w, y + h).lineTo(x, y + h).lineTo(x, y),
+                    rowHeight = h / hv,
+                    columnWidth = w / wv;
                 for (var i = 1; i < hv; i++) {
-                    p.moveTo(x, y + i * Math.round(h / hv)).lineTo(x + w, y + i * Math.round(h / hv));
+                    p.moveTo(x, y + i * rowHeight).lineTo(x + w, y + i * rowHeight);
                 }
                 for (var i = 1; i < wv; i++) {
-                    p.moveTo(x + i * Math.round(w / wv), y).lineTo(x + i * Math.round(w / wv), y + h);
+                    p.moveTo(x + i * columnWidth, y).lineTo(x + i * columnWidth, y + h);
                 }
                 return p;
             };