Refactored SafeOverwriteFileHelper into BackedUpFileWriter which itself decides on whether to revert or cleanup the temporary file and which does not have side effects on construction. Improved xmldoc. Related to Issue [WTI-487] git-svn-id: https://repos.deltares.nl/repos/WettelijkToetsInstrumentarium/trunk@4292 5a3db67b-de53-47b5-99c8-a1c30a6650e2