add defaultValue parameter to keyAs

initial.d

@@ -229,16 +229,15 @@ struct INISection
 	}
 
 	/++
-	 + Using `std.conv`, converts the value of the given key
-	 + to the given type. On conversion failure throws an
-	 + `INITypeException` with a message containing location
-	 + information.
+	 + Using `std.conv`, converts the value of *k* to *T*.
+	 + On conversion failure throws an `INITypeException`
+	 + with a message containing location information.
 	 +/
 	T
-	keyAs(T)(string k)
+	keyAs(T)(string k, string defaultValue = null)
 	{
 		try
-			return key(k).to!T();
+			return key(k, defaultValue).to!T();
 		catch (ConvException)
 			throw new INITypeException(
 				format!"unable to convert [%s].%s to %s"(name, k, T.stringof));