On my system I got
```c++
error: variable ‘std::ofstream file’ has initializer but incomplete type
std::ofstream file(fname.str().c_str());
```
This is fixed with this commit by including fstream. Previously,
this include might have happened implicitely.
Have removed the SimulatorState base class, and instead replaced with
the SimulationDatacontainer class from opm-common. The SimulatorState
objects were typcially created with a default constructor, and then
explicitly initialized with a SimulatorState::init() method. For the
SimulationDataContainer RAII is employed; the init( ) has been removed -
and there is no default constructor.
this basically means using Opm::EclipseState instead of the raw deck
for these keywords.
with this, property modifiers like ADD, MULT, COPY and friends are
supported for at least the PERM* keywords. If additional keywords are
required these can be added relatively easily as well.
no ctest regressions have been observed with this patch on my machine.
