Return full `eocs` in `convergence_test`

Release v0.9

Add more explanations for all callback analysis quantities

plotting : "total water elevation"

`plot_inital = true` does not work

Initialization of the hyperbolic approximation parameters of SGN

Roadmap KdV eq.

`plot_initial` may be confusing

Svärd-Kalisch

Error in documentation of Serre-Green-Naghdi?