Pymycobot

- Update set_gservo_round() function.
- Add pro 600 interface

- Add open/close serial function

- Fix set_joint_min(),set_joint_max() interface issue

- Add new interface: set_gservo_round()

- Fix get_joint_min_angle() and get_joint_max_angle() interface bug.
- Remove the connect function in mycobotsocket
- update demo/Server.py file
- Add new interface: get_error_information(),clear_error_information()

- Fix UltraArm interface set_gpio_state error issue