preCICE Config accepts <max-used-iterations> greater <max-iterations> if <timesteps-reused value="0"/>

[BenjaminRodenberg]

preCICE Config accepts <max-used-iterations> greater <max-iterations> if <timesteps-reused value="0"/>. However, this configuration is invalid and we should instead throw an exception: If we do not reuse any previous timesteps (<timesteps-reused value="0"/>), we cannot reuse more iterations than we actually allow to be performed in one timestep (<max-used-iterations> greater <max-iterations>).

Be aware that <max-used-iterations> may be greater than <max-iterations>, if we reuse previous timesteps.

[uekerman]

Maybe a warning would be sufficient here. Let's say you want to do a parameter study on what's the influence of timesteps-reused (we have done that before). Then, you might just set max-used-iterations to a high value and adopt timesteps-reused. Always changing both numbers might be annoying.

[BenjaminRodenberg]

When #280 is there, we could actually test these kind input errors that should trigger a preCICE error. We decided to not fix this before we can test it. When we fix it, we should directly add a test.