Update jquery.flot.stackpercent.js

Update to allow multiple chart types - ie. Line Chart over top of Stack Percent chart.

Example: http://jsfiddle.net/AuKzP/6/

Note example: This series will be a line plotted over top of the stack percent charts.

{
    "data": [
        [1, 500],
        [2, 475],
        [3, 500]
    ],
        "color": "#c0c0c0",
        "yaxis": 2,
    bars: false, //IMPORTANT
    lines: {
        show: true,
        fill: false,
        steps: false
    },
    stackpercent: null //IMPORTANT
}