Move CancelCommand to BaseViewModel.

From `PullRequestCreationViewModel`. Added `CancelCommand` to new
interface `IReactiveViewModel` and make `BaseViewModel` implement that.

Author: grokys

src/GitHub.App/ViewModels/BaseViewModel.cs

@@ -5,10 +5,15 @@
 
 namespace GitHub.ViewModels
 {
-    public class BaseViewModel : ReactiveObject, IViewModel
+    public class BaseViewModel : ReactiveObject, IReactiveViewModel
     {
         protected ObservableAsPropertyHelper<bool> isShowing;
 
+        public BaseViewModel()
+        {
+            CancelCommand = ReactiveCommand.Create();
+        }
+
         public ReactiveCommand<object> CancelCommand { get; protected set; }
         public ICommand Cancel { get { return CancelCommand; } }
 

src/GitHub.App/ViewModels/PullRequestCreationViewModel.cs

@@ -1,23 +1,11 @@
-using GitHub.Exports;
-using NullGuard;
-using System;
-using System.Collections.Generic;
-using System.ComponentModel.Composition;
-using System.Globalization;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-using ReactiveUI;
+using System.ComponentModel.Composition;
+using GitHub.Exports;
 
 namespace GitHub.ViewModels
 {
     [ExportViewModel(ViewType = UIViewType.PRCreation)]
     [PartCreationPolicy(CreationPolicy.NonShared)]
     class PullRequestCreationViewModel : BaseViewModel, IPullRequestCreationViewModel
     {
-        public PullRequestCreationViewModel()
-        {
-            CancelCommand = ReactiveCommand.Create();
-        }
     }
 }

src/GitHub.Exports.Reactive/GitHub.Exports.Reactive.csproj

@@ -102,6 +102,7 @@
     <Compile Include="ViewModels\IPullRequestCreationViewModel.cs" />
     <Compile Include="ViewModels\IPullRequestDetailViewModel.cs" />
     <Compile Include="ViewModels\IPullRequestListViewModel.cs" />
+    <Compile Include="ViewModels\IReactiveViewModel.cs" />
     <Compile Include="ViewModels\IRepositoryCreationTarget.cs" />
     <Compile Include="ViewModels\IRepositoryForm.cs" />
     <Compile Include="ViewModels\IRepositoryPublishViewModel.cs" />

src/GitHub.Exports.Reactive/ViewModels/IPullRequestCreationViewModel.cs

@@ -3,8 +3,7 @@
 namespace GitHub.ViewModels
 {
     [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Design", "CA1040:AvoidEmptyInterfaces")]
-    public interface IPullRequestCreationViewModel : IViewModel
+    public interface IPullRequestCreationViewModel : IReactiveViewModel
     {
-        ReactiveCommand<object> CancelCommand { get; }
     }
 }

src/GitHub.Exports.Reactive/ViewModels/IReactiveViewModel.cs

@@ -0,0 +1,9 @@
+using ReactiveUI;
+
+namespace GitHub.ViewModels
+{
+    public interface IReactiveViewModel : IViewModel
+    {
+        ReactiveCommand<object> CancelCommand { get; }
+    }
+}