Add support for double[] arrays in DataClass

[sjivan]

Added to SVN, thanks.

[fatzopilot]

OK, I created a patch to a recent SVN version (see attachement). Seems to work in all my cases. I'd be glad if you could include it into the official build.

[fatzopilot]

Basically, I think just the following would need to be added to add support for double[] arrays:
In DataClass.java:

    public double[] getAttributeAsDoubleArray(String property) {
        return JSOHelper.getAttributeAsDoubleArray(jsObj, property);
    }

    public static void setAttribute(JavaScriptObject elem, String attr, double[] values) {
        setAttribute(elem, attr, JSOHelper.convertToJavaScriptArray(values));
    }

and in JSOHelper.java

    public static JavaScriptObject convertToJavaScriptArray(double[] array) {
        if(array == null) return null;
        JavaScriptObject jsArray = createJavaScriptArray();
        for (int i = 0; i < array.length; i++) {
            JSOHelper.setArrayValue(jsArray, i, array[i]);
        }
        return jsArray;
    }