Added struct ParseMode to control parse behaviour.

- Introduce a very simple class ParseMode which will become a simple
   value object which can be used to control the behavior when errors
   and inconsistencies are encountered in the parse and EclipseState
   construction phases.

 - Added ParseMode instance as second argument to all parseXXX()
   methods.

opm/parser/eclipse/EclipseState/InitConfig/tests/InitConfigTest.cpp

@@ -88,7 +88,7 @@ const std::string& deckStr4 =
 
 static DeckPtr createDeck(const std::string& input) {
     Opm::Parser parser;
-    return parser.parseString(input);
+    return parser.parseString(input, Opm::ParseMode());
 }
 
 BOOST_AUTO_TEST_CASE(InitConfigTest) {