ProfilingList: add AddRange() function

Shared/ProfilingList.cs

@@ -41,6 +41,10 @@ namespace SemiColinGames {
 
     // Everything below this point is boilerplate delegation to the underlying list.
 
+    public void AddRange(IEnumerable<T> collection) {
+      items.AddRange(collection);
+    }
+
     public void Clear() {
       items.Clear();
     }