Merge pull request #2076 from thinkyhead/mendel_inverting

Use MSG_OK in M105

Marlin/Marlin_main.cpp

     #endif //FWRETRACT
 
     prepare_move();
-    //ok_to_send();
   }
 }
 
   if (setTargetedHotend(105)) return;
 
   #if HAS_TEMP_0 || HAS_TEMP_BED || defined(HEATER_0_USES_MAX6675)
-    SERIAL_PROTOCOLPGM("ok");
+    SERIAL_PROTOCOLPGM(MSG_OK);
     #if HAS_TEMP_0
       SERIAL_PROTOCOLPGM(" T:");
       SERIAL_PROTOCOL_F(degHotend(target_extruder), 1);