a8b6047b1d
this fixes some annoying inconsistencies (e.g., the recently introduced 'dyne' unit was unavailable in the opm-core version) and gets rid of some compiler abiguity errors if 'using namespace Opm::details' was used by code inside the 'Opm' namespace. Since opm-parser is a hard dependency of opm-core, the only measure which must be taken by higher-level code is to include 'opm/parser/eclipse/Units/Units.hpp' instead of 'opm/parser/eclipse/Units/ConversionFactors.hpp' or 'opm/core/utility/Units.hpp'. Note that a potentially better location for this code would be opm-common, but this would break the Windows build of opm-parser.