Updated new control's properties.

From PerspexProperty to StyledProperty.

src/Perspex.Controls/Shapes/Line.cs

@@ -9,10 +9,10 @@ namespace Perspex.Controls.Shapes
 {
     public class Line : Shape
     {
-        public static readonly PerspexProperty<Point> StartPointProperty =
+        public static readonly StyledProperty<Point> StartPointProperty =
             PerspexProperty.Register<Line, Point>("StartPoint");
 
-        public static readonly PerspexProperty<Point> EndPointProperty =
+        public static readonly StyledProperty<Point> EndPointProperty =
             PerspexProperty.Register<Line, Point>("EndPoint");
 
         private LineGeometry _geometry;

src/Perspex.Controls/Shapes/Polygon.cs

@@ -9,7 +9,7 @@ namespace Perspex.Controls.Shapes
 {
     public class Polygon : Shape
     {
-        public static readonly PerspexProperty<IList<Point>> PointsProperty =
+        public static readonly StyledProperty<IList<Point>> PointsProperty =
             PerspexProperty.Register<Polygon, IList<Point>>("Points");
 
         public IList<Point> Points

src/Perspex.Controls/Shapes/Polyline.cs

@@ -9,7 +9,7 @@ namespace Perspex.Controls.Shapes
 {
     public class Polyline: Shape
     {
-        public static readonly PerspexProperty<IList<Point>> PointsProperty =
+        public static readonly StyledProperty<IList<Point>> PointsProperty =
             PerspexProperty.Register<Polyline, IList<Point>>("Points");
 
         static Polyline()