* Update opm-common EGRID reader to support LGRs, NNCs, dual porosity, unit system info and time step filters
* Rearrange well reading code into separate class
* Update resdata library to not require an ecl_grid when reading well information. Only lgr names are needed, allows reused by opm_common reader
* Compute characteristic cell size based on active cells
* Compute cell face normal based on a suitable active cells
Using all cells as basis for face normal is fragile. Some models have highly distorted/twisted cells, but all active cells should be geometrically more stable.
