Add "About Printer" information menu.

Includes:
  *firmware version / branch / date.
  *extruder count
  *board information (name, serial details, power supply type)
  *thermistors (names, min/max temperatures)
  *printer statistics (PRINTCOUNTER details)

Thanks to @thinkyhead for contributions.

Marlin/language_en.h

@@ -520,5 +520,44 @@
 #ifndef MSG_DELTA_CALIBRATE_CENTER
   #define MSG_DELTA_CALIBRATE_CENTER          "Calibrate Center"
 #endif
+#ifndef MSG_INFO_MENU
+  #define MSG_INFO_MENU                       "About Printer"
+#endif
+#ifndef MSG_INFO_STATS_MENU
+  #define MSG_INFO_STATS_MENU                 "Printer Stats"
+#endif
+#ifndef MSG_INFO_BOARD_MENU
+  #define MSG_INFO_BOARD_MENU                 "Board Info"
+#endif
+#ifndef MSG_INFO_THERMISTOR_MENU
+  #define MSG_INFO_THERMISTOR_MENU            "Thermistors"
+#endif
+#ifndef MSG_INFO_EXTRUDERS
+  #define MSG_INFO_EXTRUDERS                  "Extruders"
+#endif
+#ifndef MSG_INFO_BAUDRATE
+  #define MSG_INFO_BAUDRATE                   "Baud"
+#endif
+#ifndef MSG_INFO_PROTOCOL
+  #define MSG_INFO_PROTOCOL                   "Protocol"
+#endif
+#ifndef MSG_INFO_TOTAL_PRINTS
+  #define MSG_INFO_TOTAL_PRINTS               "Total Prints"
+#endif
+#ifndef MSG_INFO_FINISHED_PRINTS
+  #define MSG_INFO_FINISHED_PRINTS            "Finished Prints"
+#endif
+#ifndef MSG_INFO_PRINT_TIME
+  #define MSG_INFO_PRINT_TIME                 "Total Print Time"
+#endif
+#ifndef MSG_INFO_MIN_TEMP
+  #define MSG_INFO_MIN_TEMP                   "Min Temp"
+#endif
+#ifndef MSG_INFO_MAX_TEMP
+  #define MSG_INFO_MAX_TEMP                   "Max Temp"
+#endif
+#ifndef MSG_INFO_PSU
+  #define MSG_INFO_PSU                        "Power Supply"
+#endif
 
 #endif // LANGUAGE_EN_H