request for automatic detection of parameterized List's

If we have:

```
public class Machines {
public List machines;
}

public class Machine {
public String machine_used;
public List measurements;
}
```

I have to say:

```
yamlConfig.setPropertyElementType(Machines.class, "machines", Machine.class);
yamlConfig.setPropertyElementType(Machine.class, "measurements", Measurement.class);
```

Couldn't yamlbeans conceivably use the generic parameter of the `List` as a safe default?

I can submit a pull request, if it has a decent chance of getting accepted. :)