Changed EclipseGridParser::saveEGRID() to take globalCells input

[joakim-hove]

The EclipseGridParser::saveEGRID() takes an input argument (const int * globalCell) which is used ta map out ACTNUM. This is to ensure that the saved ACTNUM field is correct with respect to cells which have been deactivated by opm-core.

Observe that the methods saveINIT() and saveEGRID_INIT() are not really functional after this PR; but they have no callers.

This PR is a start of a fix to: OPM/opm-upscaling#69, a similar PR will come for opm-porsol.

[bska]

@joakim-hove 👍 This is great! Thanks a lot. I'll merge this once the consumers in OPM-Porsol and OPM-Upscaling are updated accordingly so as not to break the build.

I just have one minor nit if you don't mind. Would you mind applying the same

static_cast<void>()

trick to the new parameters (i.e., num_cells and global_cell) of EclipseGridParser::saveEGRID() in the ! HAVE_ERT case, too? I'd rather not introduce additional "unused parameter" warnings in OPM-Core.

[bska]

Oh, one more thing. Is the filename parameter of GridManager::saveEGRID() supposed to be unused or should the implementation rather be something along the lines of

void GridManager::saveEGRID(const std::string& filename , const Opm::EclipseGridParser& deck) {
    deck.saveEGRID( filename , ug_->number_of_cells , ug_->global_cell );
}

[bska]

Thanks a lot! All tests pass in all modules so I'll merge this into master. Thanks again for taking on this task.