Fix bug when datafile was changed and nobs resulting from old dataset was...

Fix bug when datafile was changed and nobs resulting from old dataset was bigger than is possible in new dataset

matlab/utilities/dataset/initialize_dataset.m

@@ -32,7 +32,7 @@ end
 rawdata = read_variables(datafile,varobs,[],xls.sheet,xls.range);
 
 % Get the (default) number of observations.
-if isempty(nobs)
+if isempty(nobs) || rows(rawdata)<nobs+first-1 %case 2: dataset has changed
     nobs = rows(rawdata)-first+1;
 end