Merge branch 'hold_on_fix' into 'master'

plot: do not try to reset xTickLabel based on new dates if hold on was used

See merge request Dynare/dseries!43

src/@dseries/plot.m

@@ -58,12 +58,20 @@ switch ndseries
     id = get(gca,'XTick');
     if isequal(id(1),0)
         dates = strings([o.dates(1)-1,o.dates(id(2:end))]);
+        skip_relabeling=0;
     else
         ID = id(find(isint(id)));
-        set(gca,'XTick',ID);
-        dates = strings(o.dates(ID));
+        if any(ID<o.dates(1).double) || any(ID>o.dates(end).double)
+            skip_relabeling=1; %hold on was used so that axis tight did not restrict current xlim to dseries used.
+        else
+            set(gca,'XTick',ID);
+            dates = strings(o.dates(ID));
+            skip_relabeling=0;
+        end
+    end
+    if ~skip_relabeling
+        set(gca,'XTickLabel',dates);
     end
-    set(gca,'XTickLabel',dates);
   case 2
     [o0, o1] = align(o, varargin{1});
     if isequal(nvariables,1)