Include days in Graphical LCD print timer

Marlin/duration_t.h

@@ -141,14 +141,16 @@ struct duration_t {
    * @param buffer The array pointed to must be able to accommodate 10 bytes
    *
    * Output examples:
-   *  1234567890 (strlen)
-   *  1193046:59
+   *  123456789 (strlen)
+   *  99:59
+   *  11d 12:33
    */
-  void toDigital(char *buffer) const {
-    int h = this->hour(),
-        m = this->minute() % 60;
-
-    sprintf_P(buffer, PSTR("%02i:%02i"), h, m);
+  void toDigital(char *buffer, bool with_days=false) const {
+    int m = this->minute() % 60;
+    if (with_days)
+      sprintf_P(buffer, PSTR("%id %02i:%02i"), this->day(), this->hour() % 24, m);
+    else
+      sprintf_P(buffer, PSTR("%02i:%02i"), this->hour(), m);
   }
 };