Support default binding mode on direct properties.

src/Perspex.Base/DirectProperty.cs

@@ -24,11 +24,13 @@ namespace Perspex
         /// <param name="name">The name of the property.</param>
         /// <param name="getter">Gets the current value of the property.</param>
         /// <param name="setter">Sets the value of the property. May be null.</param>
+        /// <param name="metadata">The property metadata.</param>
         public DirectProperty(
             string name,
             Func<TOwner, TValue> getter,
-            Action<TOwner, TValue> setter = null)
-            : base(name, typeof(TOwner), new PropertyMetadata())
+            Action<TOwner, TValue> setter,
+            PropertyMetadata metadata)
+            : base(name, typeof(TOwner), metadata)
         {
             Contract.Requires<ArgumentNullException>(getter != null);
 

src/Perspex.Base/PerspexProperty.cs

@@ -342,16 +342,19 @@ namespace Perspex
         /// <param name="name">The name of the property.</param>
         /// <param name="getter">Gets the current value of the property.</param>
         /// <param name="setter">Sets the value of the property.</param>
+        /// <param name="defaultBindingMode">The default binding mode for the property.</param>
         /// <returns>A <see cref="PerspexProperty{TValue}"/></returns>
         public static DirectProperty<TOwner, TValue> RegisterDirect<TOwner, TValue>(
             string name,
             Func<TOwner, TValue> getter,
-            Action<TOwner, TValue> setter = null)
+            Action<TOwner, TValue> setter = null,
+            BindingMode defaultBindingMode = BindingMode.OneWay)
                 where TOwner : IPerspexObject
         {
             Contract.Requires<ArgumentNullException>(name != null);
 
-            var result = new DirectProperty<TOwner, TValue>(name, getter, setter);
+            var metadata = new PropertyMetadata(defaultBindingMode);
+            var result = new DirectProperty<TOwner, TValue>(name, getter, setter, metadata);
             PerspexPropertyRegistry.Instance.Register(typeof(TOwner), result);
             return result;
         }

tests/Perspex.Base.UnitTests/DirectPropertyTests.cs

@@ -30,7 +30,11 @@ namespace Perspex.Base.UnitTests
         [Fact]
         public void IsDirect_Property_Returns_True()
         {
-            var target = new DirectProperty<Class1, string>("test", o => null);
+            var target = new DirectProperty<Class1, string>(
+                "test", 
+                o => null, 
+                null, 
+                new PropertyMetadata());
 
             Assert.True(target.IsDirect);
         }