Fix calculation of rectangle path

The rectangle path width/height was computed using the full stroke width.
It should have been using the half stroke width instead.

Source/Basic Shapes/SvgRectangle.cs

@@ -193,8 +193,8 @@ namespace Svg
                   // Starting location which take consideration of stroke width
                   SvgPoint strokedLocation = new SvgPoint(Location.X - halfStrokeWidth, Location.Y - halfStrokeWidth);
 
-                  var width = this.Width.ToDeviceValue(renderer, UnitRenderingType.Horizontal, this) + base.StrokeWidth;
-                  var height = this.Height.ToDeviceValue(renderer, UnitRenderingType.Vertical, this) + base.StrokeWidth;
+                  var width = this.Width.ToDeviceValue(renderer, UnitRenderingType.Horizontal, this) + halfStrokeWidth;
+                  var height = this.Height.ToDeviceValue(renderer, UnitRenderingType.Vertical, this) + halfStrokeWidth;
                   
                   var rectangle = new RectangleF(strokedLocation.ToDeviceValue(renderer, this), new SizeF(width, height));