BQ Hephestos2: Heat up nozzle while leveling

Saves time and preheats the nozzle to the correct temperature (set by Cura).
Btw. the BQ support explained me the reason why they are assuming 210°C needs to set here. The reason is that the printer is just meant to be used with PLA, so they are only expecting to use exactly 210°C. Just explained them why this is incorrect when think about the possibility that Cura can set the temperature on it's own.

resources/definitions/bq_hephestos_2.def.json

@@ -14,7 +14,7 @@
     },
 
     "overrides": {
-        "machine_start_gcode": { "default_value": "; -- START GCODE --\nM800        ; Custom GCODE to fire start print procedure\nM109 S{material_print_temperature} ;Makes sure the temperature is correct before printing\n; -- end of START GCODE --" },
+        "machine_start_gcode": { "default_value": "; -- START GCODE --\nM104 S{material_print_temperature} ; Heat up extruder while leveling\nM800 ; Custom GCODE to fire start print procedure\nM109 S{material_print_temperature} ; Makes sure the temperature is correct before printing\n; -- end of START GCODE --" },
         "machine_end_gcode": { "default_value": "; -- END GCODE --\nM801        ; Custom GCODE to fire end print procedure\n; -- end of END GCODE --" },
         "machine_width": { "default_value": 210 },
         "machine_depth": { "default_value": 297 },