Add fill styling option

lib/timeline/component/LineGraph.js

@@ -1070,6 +1070,9 @@ LineGraph.prototype._drawLineGraph = function (dataset, group) {
           dFill = "M" + dataset[0].x + "," + svgHeight + " " + d + "L" + dataset[dataset.length - 1].x + "," + svgHeight;
         }
         fillPath.setAttributeNS(null, "class", group.className + " fill");
+        if(group.options.shaded.style !== undefined) {
+          fillPath.setAttributeNS(null, "style", group.options.shaded.style);
+        }
         fillPath.setAttributeNS(null, "d", dFill);
       }
       // copy properties to path for drawing.