主要实现功能：
1 tcp server并发（主要涉及文件app_lwip.c、app_tcp_server.c）
2 网线热插拔（主要涉及文件app_lwip.c、app_tcp_server.c）
3 不重启修改ip地址（主要涉及文件app_lwip.c、app_tcp_server.c、app_key.c（按键修改ip地址））
4 将lwip的数据接收从中断方式改成单独的接收任务方式（主要涉及文件app_lwip.c）
5 usb串口信息打印（115200波特率）
6 注意：使用的stm32的HAL库而不是标准库(The main functions are:
1 TCP server concurrency (mainly related to file app_lwip.c, app_tcp_server.c)
Hot plugging of 2 network lines (mainly related to documents app_lwip.c, app_tcp_server.c)
3 do not reset the IP address (mainly related to file app_lwip.c, app_tcp_server.c, app_key.c (key modify IP address))
4 change the data reception of LwIP from the interrupt mode to the individual receiving task (mainly involving the file app_lwip.c)
5 USB serial port information printing (115200 baud rate)
6 note: the HAL Library of the STM32 used instead of the standard library)