Cleanup: Remove M218

It was only enabled when multiple extruders are enabled

The firmware doesn't support it
and even if the M218 gcode could be used, the code does not compile

Firmware/Configuration.h

@@ -427,13 +427,6 @@ your extruder heater takes 2 minutes to hit the target on heating.
 //Manual homing switch locations:
 // For deltabots this means top and center of the Cartesian print volume.
 
-
-// Offset of the extruders (uncomment if using more than one and relying on firmware to position when changing).
-// The offset has to be X=0, Y=0 for the extruder 0 hotend (default extruder).
-// For the other hotends it is their distance from the extruder 0 hotend.
-// #define EXTRUDER_OFFSET_X {0.0, 20.00} // (in mm) for each extruder, offset of the hotend on the X axis
-// #define EXTRUDER_OFFSET_Y {0.0, 5.00}  // (in mm) for each extruder, offset of the hotend on the Y axis
-
 // The speed change that does not require acceleration (i.e. the software might assume it can be done instantaneously)
 #define DEFAULT_XJERK                10       // (mm/sec)
 #define DEFAULT_YJERK                10       // (mm/sec)

Firmware/Marlin_main.cpp

@@ -216,16 +216,6 @@ float min_pos[3] = { X_MIN_POS, Y_MIN_POS, Z_MIN_POS };
 float max_pos[3] = { X_MAX_POS, Y_MAX_POS, Z_MAX_POS };
 bool axis_known_position[3] = {false, false, false};
 
-// Extruder offset
-#if EXTRUDERS > 1
-  #define NUM_EXTRUDER_OFFSETS 2 // only in XY plane
-float extruder_offset[NUM_EXTRUDER_OFFSETS][EXTRUDERS] = {
-#if defined(EXTRUDER_OFFSET_X) && defined(EXTRUDER_OFFSET_Y)
-  EXTRUDER_OFFSET_X, EXTRUDER_OFFSET_Y
-#endif
-};
-#endif
-
 int fanSpeed=0;
 uint8_t newFanSpeed = 0;
 
@@ -3985,7 +3975,6 @@ extern uint8_t st_backlash_y;
 //!@n M208 - set recover=unretract length S[positive mm surplus to the M207 S*] F[feedrate mm/sec]
 //!@n M209 - S<1=true/0=false> enable automatic retract detect if the slicer did not support G10/11: every normal extrude-only move will be classified as retract depending on the direction.
 //!@n M214 - Set Arc Parameters (Use M500 to store in eeprom) P<MM_PER_ARC_SEGMENT> S<MIN_MM_PER_ARC_SEGMENT> R<MIN_ARC_SEGMENTS> F<ARC_SEGMENTS_PER_SEC>
-//!@n M218 - set hotend offset (in mm): T<extruder_number> X<offset_on_X> Y<offset_on_Y>
 //!@n M220 S<factor in percent>- set speed factor override percentage
 //!@n M221 S<factor in percent>- set extrude factor override percentage
 //!@n M226 P<pin number> S<pin state>- Wait until the specified pin reaches the state required
@@ -7065,45 +7054,6 @@ Sigma_Exit:
         cs.min_arc_segments = r;
         cs.arc_segments_per_sec = f;
     }break;
-    #if EXTRUDERS > 1
-
-    /*!
-	### M218 - Set hotend offset <a href="https://reprap.org/wiki/G-code#M218:_Set_Hotend_Offset">M218: Set Hotend Offset</a>
-	In Prusa Firmware this G-code is only active if `EXTRUDERS` is higher then 1 in the source code. On Original i3 Prusa MK2/s MK2.5/s MK3/s it is not active.
-    #### Usage
-    
-        M218 [ X | Y ]
-        
-    #### Parameters
-    - `X` - X offset
-    - `Y` - Y offset
-    */
-    case 218: // M218 - set hotend offset (in mm), T<extruder_number> X<offset_on_X> Y<offset_on_Y>
-    {
-      uint8_t extruder;
-      if(setTargetedHotend(218, extruder)){
-        break;
-      }
-      if(code_seen('X'))
-      {
-        extruder_offset[X_AXIS][extruder] = code_value();
-      }
-      if(code_seen('Y'))
-      {
-        extruder_offset[Y_AXIS][extruder] = code_value();
-      }
-      SERIAL_ECHO_START;
-      SERIAL_ECHORPGM(MSG_HOTEND_OFFSET);
-      for(extruder = 0; extruder < EXTRUDERS; extruder++)
-      {
-         SERIAL_ECHO(" ");
-         SERIAL_ECHO(extruder_offset[X_AXIS][extruder]);
-         SERIAL_ECHO(",");
-         SERIAL_ECHO(extruder_offset[Y_AXIS][extruder]);
-      }
-      SERIAL_ECHOLN("");
-    }break;
-    #endif
 
     /*!
 	### M220 Set feedrate percentage <a href="https://reprap.org/wiki/G-code#M220:_Set_speed_factor_override_percentage">M220: Set speed factor override percentage</a>