New functions

Example code

if __name__ == '__main__':
    m = MotorDriver()
    time.sleep(1)
    print("ttest code")
    try:
        print("this is a motor driver test code")
        
        #Parameter 1: motor select:'MA', 'MB', 'MC', 'MD'
        #Parameter 2: turn dir:'forward', 'backward'
        #Parameter 3: motor speed: 0-100
        #Parameter 4: Running time: >0
        print("motor A forward, speed 100%, Run for 2S, then stop")
        m.MotorRun('MA', 'forward', 100, 20)
        #print("motor A backward, speed 100%, Run for 2S, then stop")
        #m.MotorRun('MA', 'backward', 100, 2)
        #print("motor B forward, speed 50%, Run for 4S, then stop")
        #m.MotorRun('MB', 'forward', 50, 4)
        #print("motor B forward, speed 50%, Run for 4S, then stop")
        #m.MotorRun('MB', 'backward', 50, 4)
        #time.sleep(2)
        
    except KeyboardInterrupt:
        exit()