Show manual extrusion moves as relative in LCD

- Implements FR#11724
- Old behavior can be restored by commenting out MANUAL_E_MOVES_RELATIVE

Marlin/Configuration_adv.h

 
 #if ENABLED(ULTIPANEL)
   #define MANUAL_FEEDRATE {50*60, 50*60, 4*60, 60} // Feedrates for manual moves along X, Y, Z, E from panel
+  #define MANUAL_E_MOVES_RELATIVE // Show LCD extruder moves as relative rather than absolute positions
   #define ULTIPANEL_FEEDMULTIPLY  // Comment to disable setting feedrate multiplier via encoder
 #endif
 

Marlin/src/config/default/Configuration_adv.h

 
 #if ENABLED(ULTIPANEL)
   #define MANUAL_FEEDRATE {50*60, 50*60, 4*60, 60} // Feedrates for manual moves along X, Y, Z, E from panel
+  #define MANUAL_E_MOVES_RELATIVE // Show LCD extruder moves as relative rather than absolute positions
   #define ULTIPANEL_FEEDMULTIPLY  // Comment to disable setting feedrate multiplier via encoder
 #endif
 

Marlin/src/lcd/ultralcd.cpp

     #define manual_move_e_index 0
   #endif
 
+  #if ENABLED(MANUAL_E_MOVES_RELATIVE)
+    float manual_move_e_origin = 0;
+  #endif
+
   #if IS_KINEMATIC
     bool processing_manual_move = false;
     float manual_move_offset = 0;
         #if IS_KINEMATIC
           + manual_move_offset
         #endif
+        #if ENABLED(MANUAL_E_MOVES_RELATIVE)
+          - manual_move_e_origin
+        #endif
       ));
     }
   }
         case Z_AXIS:
           STATIC_ITEM(MSG_MOVE_Z, true, true); break;
         default:
-          STATIC_ITEM(MSG_MOVE_E, true, true); break;
+          #if ENABLED(MANUAL_E_MOVES_RELATIVE)
+            manual_move_e_origin = current_position[E_AXIS];
+          #endif
+          STATIC_ITEM(MSG_MOVE_E, true, true);
+          break;
       }
     }
     MENU_BACK(MSG_MOVE_AXIS);