Alternative 'getUnits' to 'getDeckUnitSystem'

getDeckUnitSystem largely implies getting an *identifier* to the unit
system used in the deck, where the actual object returned has conversion
features to/from SI as well. Augment EclipseState's interface with the
simpler getUnits name.

opm/parser/eclipse/EclipseState/EclipseState.cpp

@@ -106,6 +106,10 @@ namespace Opm {
         return m_deckUnitSystem;
     }
 
+    const UnitSystem& EclipseState::getUnits() const {
+        return m_deckUnitSystem;
+    }
+
     EclipseGridConstPtr EclipseState::getInputGrid() const {
         return m_inputGrid;
     }

opm/parser/eclipse/EclipseState/EclipseState.hpp

@@ -104,6 +104,7 @@ namespace Opm {
         // units because internally to opm-parser everything is represented by SI
         // units...
         const UnitSystem& getDeckUnitSystem() const;
+        const UnitSystem& getUnits() const;
 
         /// [deprecated]
         void applyModifierDeck(std::shared_ptr<const Deck>);