black-oil: some fixes to the model and fluid system
add VTK output module to write the black oil parameters
black oil fluid system: make sure oilSaturationPressure(XoG) == flashMassFracInOil_(p_sat)
blackoil model: fixes
implicit models: use better weight heuristics for the primary variables
cmake: move FindMETIS before the grids

this should fix an reconfigure issue with alugrid...
update reference solutions