Report on MINPV processing

[joakim-hove]

Hello;

I am about to write some code to report on MINPV processing, specifically on the number of cells removed and the volume "lost". This can either be reported where it happens in Minpvprocessor.hpp - or alternatively the details can be exported in a std::vector<....> and logged elsewhere (e.g. opm-simulators). Myself I am inclined to do the last thing - but open for other opinions.

[blattms]

As long as CpGrid stays usable without too many ecl/opm-isms I am fine.

Would the information be used for anything else besides for logging? If not, why complicate the code. Just add the possibility to pass in a logger and provide one that does nothing as the default.