Add project files.

Framework/Core/Extensions/ICollectionExtensions.cs

@@ -0,0 +1,15 @@
+using System.Collections.Generic;
+
+namespace TheXamlGuy.Framework.Core
+{
+    public static class ICollectionExtensions
+    {
+        public static void AddRange<T>(this ICollection<T> target, IEnumerable<T> source)
+        {
+            foreach (T item in source)
+            {
+                target.Add(item);
+            }
+        }
+    }
+}