ad few more manual updates of outdated, mistyped or no longer available URLs

src/update.cpp

@@ -124,7 +124,7 @@ void Update::init()
 void Update::set_units(const char *style)
 {
   // physical constants from:
-  // http://physics.nist.gov/cuu/Constants/Table/allascii.txt
+  // https://physics.nist.gov/cuu/Constants/Table/allascii.txt
   // using thermochemical calorie = 4.184 J
 
   double dt_old = dt;