inconsistency in formatOccData

[FrancescaMancini]

When only survey is specified in formatOccData, the function returns occDetdata$TP as athe actual year value (e.g. 1970). When both survey and closure_period are specified occDetdata$TP is returned as an integer from 1 to the number of years (e.g. 42). This causes issues with wrappeR. We either need to update the documentation so that this is clear or edit formatOccData so that it always returns the actual year.