Support for distinct E factors

Marlin/example_configurations/Felix/DUAL/Configuration.h

@@ -145,6 +145,9 @@
 // :[1, 2, 3, 4]
 #define EXTRUDERS 2
 
+// Enable if your E steppers or extruder gear ratios are not identical
+//#define DISTINCT_E_FACTORS
+
 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
@@ -455,26 +458,31 @@
  *
  * These settings can be reset by M502
  *
+ * You can set distinct factors for each E stepper, if needed.
+ * If fewer factors are given, the last will apply to the rest.
+ *
  * Note that if EEPROM is enabled, saved values will override these.
  */
 
 /**
  * Default Axis Steps Per Unit (steps/mm)
  * Override with M92
+ *                                      X, Y, Z, E0 [, E1[, E2[, E3]]]
  */
 #define DEFAULT_AXIS_STEPS_PER_UNIT   { 76.190476, 76.190476, 1600, 164 }
 
 /**
  * Default Max Feed Rate (mm/s)
  * Override with M203
+ *                                      X, Y, Z, E0 [, E1[, E2[, E3]]]
  */
 #define DEFAULT_MAX_FEEDRATE          { 500, 500, 5, 25 }
 
 /**
  * Default Max Acceleration (change/s) change = mm/s
+ * (Maximum start speed for accelerated moves)
  * Override with M201
- *
- * Maximum start speed for accelerated moves: { X, Y, Z, E }
+ *                                      X, Y, Z, E0 [, E1[, E2[, E3]]]
  */
 #define DEFAULT_MAX_ACCELERATION      { 5000, 5000, 100, 80000 }