by default, this just checks if the saturation of the incriminating
phase is larger than 0, but in some cases (i.e., black-oil) the
calling code might have a different opinion: E.g., the black-oil model
looks at the primary variables to determine the phase presence.
so far, using function evaluation objects instead of primitive
floating point scalars only worked for trivial parameter caches which
do not store any values (most of the time, this means that the
ParameterCache is `NullParameterCache`), or it explicitly did not work
(like for `Spe5ParameterCache`). this patch fixes the problem by
making the parameter caches of fluid systems template classes which
are templated on the type of scalar values. On the flipside, this
requires changes to all downstream modules that use fluid systems.
this patch removes the in-file lists in favor of a global list of in
the COPYING file. this is done because (a) maintaining a list of
authors at the beginning of each source file is a major pain in the
a**, (b) for this reason, the list of authors was not accurate in
about 85% of all cases where more than one person was involved and (c)
this list is not legally binding in any way (the copyright is at the
person who authored a given change; if these lists had any legal
relevance, one could "aquire" the copyright of the module by forking
it and replacing the lists...)
if the base fluid state returns a reference, the overlay fluid state
should just pass it through instead if copying it. The difference
became relevant with the introduction of Evaluations for localized
AD. (is not relevant if Scalars are floating point values, which was
the only choice when the overlay fluid states were written.)
