hopefully this makes standalone `ebos` arrive at the same initial
condition as `flow_ebos` if both, SWATINIT and threshold pressures are
enabled. we need to calculate the initial condition twice either
threshold pressures and SWATINIT are enabled. (`ebos` and `flow_ebos`
diverged after OPM/opm-core#1129.)
the proposed patch is a kludge IMO, but in the light that in my
opinion, SWATINIT and threshold pressures are both physically not
justified and given the fact that SWATINIT must not be considered for
the threshold pressues should be considered to be a bug of the
reference simulator, I think the patch is okay.
we now store the maximum oil-water capillary pressure and apply it to
the material parameters later. this simplifies things within the
EquilInitializer somewhat and also allows external code (i.e.,
flow_ebos) to choose when SWATINIT gets applied.
