Add createSymbols Property to AreaChart / StackedAreaChart

LineChart has a createSymbols Property to switch on/off creation of symbols where data points are in the chart.

The same property would be nice to have on AreaChart/StackedAreaChart as well, since it is way more easy to get rid of the symbols with such a property in comparison to be forced doing this via CSS and in terms of API it would be more consistent with LineChart.

Requested API Change should mirror the one in LineChart

Desired API change:

 /**
     * Indicates whether symbols for data points will be created or not.
     *
     * @return true if symbols for data points will be created and false otherwise.
     */
    public final boolean getCreateSymbols() { return createSymbols.getValue(); }
    public final void setCreateSymbols(boolean value) { createSymbols.setValue(value); }
    public final BooleanProperty createSymbolsProperty() { return createSymbols; }

Desired additional CSS property:

-fx-create-symbols