problems: get rid of the meanK() method

for finite-volume discretizations this is replaced by
intersectionIntrinsicPermeability(). By default it just averages the FV
permeabilities, but more advanced stuff like permeability multipliers
can be implemented this way.
ECL problem: use logically cartesian cell indices to retrieve data from the deck

Before, it only worked if all cells were active. Also, take the NTG
and MULTPV keywords into account and prepare for permeability
multipliers.
fix the end-of-iteration output handling of the Newton method

I've go no idea who did this ;) Honestly, I must have been
dream-walking...