Strip "I" from type name when generating a variable name.

src/Libraries/NRefactory/ICSharpCode.NRefactory.CSharp.Refactoring/CodeActions/CreateMethodDeclarationAction.cs

@@ -363,7 +363,10 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 				case "System.Action":
 					return "action";
 			}
-			return returnType.Name;
+			if (returnType.Kind == TypeKind.Interface && returnType.Name.StartsWith("I", System.StringComparison.Ordinal))
+				return returnType.Name.Substring(1);
+			else
+				return returnType.Name;
 		}
 		
 		string GetMethodName(InvocationExpression invocation)