Broken KdV tests

[ChrisRackauckas]

Currently commented out because it stalls on CI

https://github.com/JuliaDiffEq/DiffEqOperators.jl/blob/master/test/runtests.jl#L11

[ChrisRackauckas]

KdV tests are now running, but they are still broken and do not converge correctly.

[ChrisRackauckas]

Since the single soluton works and it's just the dual soluton tests that are failing, but those are converging to something, I wonder if the analytical solution is written down wrong.

[shivin9]

well whatever it is, the solution is some form of a travelling wave only. But currently we see the waves 'splashing'. Don't know why that is happening when the 1D-Advection problem is getting solved correctly