Sets the method of automatically calculating the candle width and
sends a
RendererChangeEvent to all registered listeners.
WIDTHMETHOD_AVERAGE: Divides the entire display (ignoring
scale factor) by the number of items, and uses this as the available
width.
WIDTHMETHOD_SMALLEST: Checks the interval between each
item, and uses the smallest as the available width.
WIDTHMETHOD_INTERVALDATA: Assumes that the dataset supports
the IntervalXYDataset interface, and uses the startXValue - endXValue as
the available width.