* Remove use of RifEnsembleStatisticsReader
* Add RimSummaryAddressSelector and RimEnsembleCrossPlotStatisticsCase
* Remove RifEnsembleStatisticsReader
* Add support for cross plot x-axis selection
* Support source stepping on ensemble cross plot curves
* Add isXAxisSummaryVector
- remove the gsl::not_null for pointer to curve data
- For summary cases linked to a grid model case, do not try to read the original location of file if grid file location is not valid (will happen when a project file is moved)