[bugfix] Remove raw pointers for the views in CpGrid

[blattms]

This pointers were dangling after a grid was copied and the original one removed. Fortunatley, we did not do this in productive code.

This approach uses a boolean to see whether the current view is distributed or not. This way we can use default copy constructors.

Unfortunately. there are a lot of branches now. Let's see what that costs.

[blattms]

jenkins build this serial please

[blattms]

benchmark please

[ytelses]

Benchmark result overview:

Test	Configuration	Relative
opm-git	OPM Benchmark: drogon - Threads: 1	1.002
opm-git	OPM Benchmark: drogon - Threads: 8	0.957
opm-git	OPM Benchmark: punqs3 - Threads: 1	0.988
opm-git	OPM Benchmark: punqs3 - Threads: 8	0.998
opm-git	OPM Benchmark: smeaheia - Threads: 1	0.998
opm-git	OPM Benchmark: smeaheia - Threads: 8	1.015
opm-git	OPM Benchmark: spe10_model_1 - Threads: 1	0.98
opm-git	OPM Benchmark: spe10_model_1 - Threads: 8	0.991
opm-git	OPM Benchmark: flow_mpi_extra - Threads: 1	0.997
opm-git	OPM Benchmark: flow_mpi_extra - Threads: 8	1.059
opm-git	OPM Benchmark: flow_mpi_norne - Threads: 1	1.008
opm-git	OPM Benchmark: flow_mpi_norne - Threads: 8	1.088
opm-git	OPM Benchmark: flow_mpi_norne_4c_msw - Threads: 1 - FOPT (Total Oil Production At End Of Run)	1
opm-git	OPM Benchmark: flow_mpi_norne_4c_msw - Threads: 8 - FOPT (Total Oil Production At End Of Run)	1.003

• Speed-up = Total time master / Total time pull request. Above 1.0 is an improvement. *

View result details @ https://www.ytelses.com/opm/?page=result&id=2708