Update: assured compatibility of functions 'gfCompleteMonthlyCases.R', 'gfComputeLinearModel.R', 'gfImputeMissingValue.R',
'gfJulendat.R', "gfNonNaStations.R', 'gfOutputData.R', 'gfRejectLowQuality.R', 'gfRun.R' and 'gfValidNaThreshold.R'.