Bondtech modifications

Tweaks for using Bondtech's MK3 hotend mount.
See https://github.com/BondtechAB/Bondtech-Prusa-Firmware/tree/Bondtech-MK3-FW393

Firmware/Marlin_main.cpp

@@ -2231,12 +2231,8 @@ bool calibrate_z_auto()
 	plan_buffer_line_destinationXYZE(feedrate / 60);
 	st_synchronize();
 	enable_endstops(endstops_enabled);
-	if (PRINTER_TYPE == PRINTER_MK3) {
-		current_position[Z_AXIS] = Z_MAX_POS + 2.0;
-	}
-	else {
-		current_position[Z_AXIS] = Z_MAX_POS + 9.0;
-	}
+
+	current_position[Z_AXIS] = Z_MAX_POS + 3.0;
 	plan_set_position_curposXYZE();
 	return true;
 }

Firmware/variants/1_75mm_MK3S-EINSy10a-E3Dv6full.h

@@ -43,7 +43,7 @@
 
 // Steps per unit {X,Y,Z,E}
 //#define DEFAULT_AXIS_STEPS_PER_UNIT   {100,100,3200/8,140}
-#define DEFAULT_AXIS_STEPS_PER_UNIT   {100,100,3200/8,280}
+#define DEFAULT_AXIS_STEPS_PER_UNIT   {100,100,3200/8,830}
 //#define DEFAULT_AXIS_STEPS_PER_UNIT   {100,100,3200/8,560}
 
 // Endstop inverting
@@ -356,11 +356,11 @@
 // Load filament commands
 #define LOAD_FILAMENT_0 "M83"
 #define LOAD_FILAMENT_1 "G1 E70 F400"
-#define LOAD_FILAMENT_2 "G1 E40 F100"
+#define LOAD_FILAMENT_2 "G1 E50 F100"
 
 // Unload filament commands
 #define UNLOAD_FILAMENT_0 "M83"
-#define UNLOAD_FILAMENT_1 "G1 E-80 F7000"
+#define UNLOAD_FILAMENT_1 "G1 E-100 F7000"
 
 /*------------------------------------
  CHANGE FILAMENT SETTINGS
@@ -376,7 +376,7 @@
 #define FILAMENTCHANGE_FINALRETRACT -80
 
 #define FILAMENTCHANGE_FIRSTFEED 70 //E distance in mm for fast filament loading sequence used used in filament change (M600)
-#define FILAMENTCHANGE_FINALFEED 25 //E distance in mm for slow filament loading sequence used used in filament change (M600) and filament load (M701) 
+#define FILAMENTCHANGE_FINALFEED 35 //E distance in mm for slow filament loading sequence used used in filament change (M600) and filament load (M701) 
 #define FILAMENTCHANGE_RECFEED 5
 
 #define FILAMENTCHANGE_XYFEED 50