Reverting change to make RegisterSetup abstract

MvvmCross.Forms/Platforms/Ios/Core/MvxFormsApplicationDelegate.cs

@@ -98,7 +98,9 @@ namespace MvvmCross.Forms.Platforms.Ios.Core
             LifetimeChanged?.Invoke(this, new MvxLifetimeEventArgs(which));
         }
 
-        protected abstract void RegisterSetup();
+        protected virtual void RegisterSetup()
+        {
+        }
 
         public event EventHandler<MvxLifetimeEventArgs> LifetimeChanged;
     }

MvvmCross.Forms/Platforms/Mac/Core/MvxFormsApplicationDelegate.cs

@@ -93,7 +93,9 @@ namespace MvvmCross.Forms.Platforms.Mac.Core
             LifetimeChanged?.Invoke(this, new MvxLifetimeEventArgs(which));
         }
 
-        protected abstract void RegisterSetup();
+        protected virtual void RegisterSetup()
+        {
+        }
 
         public event EventHandler<MvxLifetimeEventArgs> LifetimeChanged;
     }

MvvmCross/Platforms/Android/Views/MvxAndroidApplication.cs

@@ -27,7 +27,9 @@ namespace MvvmCross.Platforms.Android.Views
             RegisterSetup();
         }
 
-        protected abstract void RegisterSetup();
+        protected virtual void RegisterSetup()
+        {
+        }
     }
 
     public abstract class MvxAndroidApplication<TMvxAndroidSetup, TApplication> : MvxAndroidApplication

MvvmCross/Platforms/Ios/Core/MvxApplicationDelegate.cs

@@ -64,7 +64,9 @@ namespace MvvmCross.Platforms.Ios.Core
             return null;
         }
 
-        protected abstract void RegisterSetup();
+        protected virtual void RegisterSetup()
+        {
+        }
 
         private void FireLifetimeChanged(MvxLifetimeEvent which)
         {

MvvmCross/Platforms/Mac/Core/MvxApplicationDelegate.cs

@@ -73,7 +73,9 @@ namespace MvvmCross.Platforms.Mac.Core
             LifetimeChanged?.Invoke(this, new MvxLifetimeEventArgs(which));
         }
 
-        protected abstract void RegisterSetup();
+        protected virtual void RegisterSetup()
+        {
+        }
 
         public event EventHandler<MvxLifetimeEventArgs> LifetimeChanged;
     }

MvvmCross/Platforms/Tvos/Core/MvxApplicationDelegate.cs

@@ -69,7 +69,9 @@ namespace MvvmCross.Platforms.Tvos.Core
             handler?.Invoke(this, new MvxLifetimeEventArgs(which));
         }
 
-        protected abstract void RegisterSetup();
+        protected virtual void RegisterSetup()
+        {
+        }
 
         public event EventHandler<MvxLifetimeEventArgs> LifetimeChanged;
     }

MvvmCross/Platforms/Uap/Views/MvxApplication.cs

@@ -145,6 +145,8 @@ namespace MvvmCross.Platforms.Uap.Views
             return Task.CompletedTask;
         }
 
-        protected abstract void RegisterSetup();
+        protected virtual void RegisterSetup()
+        {
+        }
     }
 }

MvvmCross/Platforms/Wpf/Views/MvxApplication.cs

@@ -32,6 +32,8 @@ namespace MvvmCross.Platforms.Wpf.Views
             return null;
         }
 
-        protected abstract void RegisterSetup();
+        protected virtual void RegisterSetup()
+        {
+        }
     }
 }