parameter support

like requested in #43 and some more xml validation stuff :).

![parameter_support](https://f.cloud.github.com/assets/1011712/432054/07057514-ae9b-11e2-94d0-c5c70591e88e.png)
![parameter_support_1](https://f.cloud.github.com/assets/1011712/432055/07093000-ae9b-11e2-9229-dd8b3dddc919.png)