Implement IFormattable for RoundedDouble so that it is possible to give a custom format and culture to a RoundedDouble while still be able to use to default formatting of some double values (Infinity) Related to Issue [WTI-453] git-svn-id: https://repos.deltares.nl/repos/WettelijkToetsInstrumentarium/trunk@2886 5a3db67b-de53-47b5-99c8-a1c30a6650e2