* Moved Input and Output placeholders from Ringtoets.Integration.Data to Ringtoets.Common.Placeholder. * Refactored PipingFailureMechanism to be more consistent with FailureMechanismPlaceholder. Related to Issue [WTI-171] git-svn-id: https://repos.deltares.nl/repos/WettelijkToetsInstrumentarium/trunk@901 5a3db67b-de53-47b5-99c8-a1c30a6650e2