Some files define time shift as double, not int

include/layereddataz.h

@@ -26,7 +26,7 @@ class LayeredDataZ: public NCFuncs
   {
    static const MString pref = "LayeredDataZ::NC::ReadTimes";
    if(!*this) return Error(pref, "Dataset not open");
-   std::vector<int8> time;
+   std::vector<double> time;
 
    {
     auto ret = Read(tname, time);
@@ -46,7 +46,7 @@ class LayeredDataZ: public NCFuncs
    }
 
    times.resize(time.size());
-   for(size_t i = 0; i < times.size(); i++) times[i] = refdate + static_cast<time_t>(time[i]) * step;
+   for(size_t i = 0; i < time.size(); i++) times[i] = refdate + static_cast<time_t>(time[i] * step);
    return Error();
   }