This commit adds a level of indirection to the existing group-level
data (active controls and guiderates), and adds a new 'NodeData'
level to the 'data::' protocol for transporting values from the
simulator to the output layer.
Update all call sites and users accordingly.
calculated and stored as private data members in EclipseGrid.
The API for the class is unchanged except for some minor changes for exportACTNUM, exportZCORN and exportCOORD.
These changes have triggered some very few modifications in the opm-grid and opm-simulators repo.