gcode: Automatically call reset_last_position() on a toolhead set_position()

Generate a "toolhead:set_position" event on a call to
toolhead.set_position() and use that event to automatically call
gcode.reset_last_position().

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

klippy/toolhead.py

@@ -400,6 +400,7 @@ class ToolHead:
         self.trapq_free_moves(self.trapq, self.reactor.NEVER)
         self.commanded_pos[:] = newpos
         self.kin.set_position(newpos, homing_axes)
+        self.printer.send_event("toolhead:set_position")
     def move(self, newpos, speed):
         move = Move(self, self.commanded_pos, newpos, speed)
         if not move.move_d: