gcode: Reset extrude_factor and extruder position on a tool change

The extrude_factor and extruder position are specific to the current
extruder, so reset them to default values on a Tn command.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

klippy/gcode.py

@@ -395,6 +395,8 @@ class GCodeParser:
             raise error(str(e))
         self.extruder = e
         self.reset_last_position()
+        self.extrude_factor = 1.
+        self.base_position[3] = self.last_position[3]
         self.run_script(self.extruder.get_activate_gcode(True))
     def cmd_mux(self, params):
         key, values = self.mux_commands[params['#command']]