[BUG] CandleStick does not utilize filled Style

[NathanSWard]

Describe the bug
When creating a CandleStick such as:

let candle = CandleStick::new(
                    ...,
                    GREEN.filled(),
                    RED.filled(),
                    15,
                );

Even though the provided ShapeStyle is filled, the graph does not render the rectangle as filled.

To Reproduce
Use the current candlestick example and just add .filled() to the colors.

Version Information
0.3.1

NOTE
The logic is due to this: https://github.com/38/plotters/blob/72479a086a2f50b4c73d6e613cbf53b7aea604f5/src/element/candlestick.rs#L81
where false is always passed as the fill parameter for draw_rect.

[38]

We are going to merge PR #290 and release new version. Closing the issue for now.