[bug] the rectangle is not rendered and editable as a rectangle

[leiii]

maptalks's version and what browser you use?

1.00-rc12

Issue description

• Draw a rectangle using the rectangle drawing tool
• Render the rectangle and open the editor for the rectangle
• The right bottom angle is not 90 degree, i.e., the element is not a rectangle (see the pic above)

Please provide a reproduction URL (on any jsfiddle like site)

[leiii]

A similar issue exits in the circle drawing, here is an example based on the official doc:

[surfsky]

This bug exists now
var rectangle = new maptalks.Rectangle(center.add(-0.018, 0.012), 800000, 700000, {
symbol: {
lineColor: '#34495e',
lineWidth: 2,
polygonFill: '#34495e',
polygonOpacity: 0.4
}
});
Suggest provide Rectangle(extent) contructor.

该bug现在还存在，如图所示。
另外，建议提供类似 Rectangle(extent) 的构造方法，我们经常只知道矩形的4个经纬度坐标，而不知道怎么转化为原构造函数中的宽度和高度。

[surfsky]

This bug exists now

        var rectangle = new maptalks.Rectangle(center.add(-0.018, 0.012), 800000, 700000, {
            symbol: {
                lineColor: '#34495e',
                lineWidth: 2,
                polygonFill: '#34495e',
                polygonOpacity: 0.4
            }
        });

Suggest provide Rectangle(extent) contructor.

该bug现在还存在，如图所示。
另外，建议提供类似 Rectangle(extent) 的构造方法，我们经常只知道矩形的4个经纬度坐标，而不知道怎么转化为原构造函数中的宽度和高度。