Added ViewModelBase class.

And make all VMs inherit from this instead of directly from
`ReactiveObject`.

Author: grokys

src/GitHub.App/GitHub.App.csproj

@@ -132,6 +132,7 @@
     <Reference Include="WindowsBase" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="ViewModels\ViewModelBase.cs" />
     <None Include="..\..\script\Key.snk" Condition="$(Buildtype) == 'Internal'">
       <Link>Key.snk</Link>
     </None>

src/GitHub.App/ViewModels/DialogViewModelBase.cs

@@ -1,17 +1,15 @@
-using System.Windows.Input;
-using ReactiveUI;
-using NullGuard;
-using GitHub.UI;
-using System;
+using System;
 using System.Reactive;
 using GitHub.Extensions.Reactive;
+using NullGuard;
+using ReactiveUI;
 
 namespace GitHub.ViewModels
 {
     /// <summary>
     /// Base class for view models that can be dismissed, such as dialogs.
     /// </summary>
-    public abstract class DialogViewModelBase : ReactiveObject, IDialogViewModel, IHasBusy
+    public abstract class DialogViewModelBase : ViewModelBase, IDialogViewModel, IHasBusy
     {
         protected ObservableAsPropertyHelper<bool> isShowing;
         string title;
@@ -51,10 +49,5 @@ public bool IsBusy
 
         /// <inheritdoc/>
         IObservable<Unit> IHasCancel.Cancel => Cancel.SelectUnit();
-
-        /// <inheritdoc/>
-        public virtual void Initialize([AllowNull] ViewWithData data)
-        {
-        }
     }
 }

src/GitHub.App/ViewModels/PanePageViewModelBase.cs

@@ -7,7 +7,7 @@ namespace GitHub.ViewModels
     /// <summary>
     /// Base class for view models that appear as a page in a navigable pane, such as the GitHub pane.
     /// </summary>
-    public class PanePageViewModelBase : ReactiveObject, IPanePageViewModel
+    public class PanePageViewModelBase : ViewModelBase, IPanePageViewModel
     {
         string title;
 
@@ -25,10 +25,5 @@ public string Title
             get { return title; }
             protected set { this.RaiseAndSetIfChanged(ref title, value); }
         }
-
-        /// <inheritdoc/>
-        public virtual void Initialize([AllowNull] ViewWithData data)
-        {
-        }
     }
 }

src/GitHub.App/ViewModels/ViewModelBase.cs

@@ -0,0 +1,18 @@
+using System;
+using GitHub.UI;
+using NullGuard;
+using ReactiveUI;
+
+namespace GitHub.ViewModels
+{
+    /// <summary>
+    /// Base class for view models.
+    /// </summary>
+    public abstract class ViewModelBase : ReactiveObject, IViewModel
+    {
+        /// <inheritdoc/>
+        public virtual void Initialize([AllowNull] ViewWithData data)
+        {
+        }
+    }
+}