Fix weno to work with standard examples
Currently working examples
- advection + sine
- advection + bump
- burgers + sine
- burgers + gaussian
- euler + smooth
- euler + sod shocktube
- sr euler + sod shocktube
- sr euler + blast wave 1
Blast wave 2 test is not working, but none of the other methods is working in this case either. The overall quality of the weno implementation is also not good. Although I think the weno implementation together with the splitting technique is correct, the results are still very poor. But I don't see where the problem is ...