Make Builder support fluids via containers/pipes

Close #1795.

*btw fix some code in engine's gui.*

**I'd already said that I'm a crazy painter?**
![screenshot from 2014-06-02 21 21 50](https://cloud.githubusercontent.com/assets/1416030/3148050/510ad50c-ea5c-11e3-9e2a-4a52a97da56a.png)