the opm-material classes are the ones which are now used by
opm-autodiff and this patch makes it much easier to keep the opm-core
and opm-autodiff results consistent. Also, the opm-material classes
seem to be a bit faster than the opm-core ones (see
https://github.com/OPM/opm-autodiff/pull/576)
I ran the usual array of tests with `flow`: SPE1, SPE3, SPE9 and Norne
all produce the same results at the identical runtime (modulo noise)
and also "Model 2" seems to work.
Several files stopped compiling due to relying on opm-parser headers
doing includes. From opm-parser PR-656
https://github.com/OPM/opm-parser/pull/656 this assumption is no longer
valid.
