闫刚 qgroundcontrol地面站通信流代码架构

qgroundcontrol开发者文档中说明了qgc中的各个链路流向在文档中说明的很清楚，下面配套源代码进行讲解整个qgc地面站的数据流向过程.

qgroundcontrol通信

在 https://dev.qgroundcontrol.com/en/communication_flow.html 中描述如下

Description of the high level communication flow which takes place during a vehicle auto-connect.

    LinkManager always has a UDP link open waiting for a Vehicle heartbeat
    LinkManager detects a new known device (Pixhawk, SiK Radio, PX4 Flow) connected to computer
        Creates a new SerialLink connected to the device
    Bytes comes through Link and are sent to MAVLinkProtocol
    MAVLinkProtocol converts the bytes into a MAVLink message
    If the message is a HEARTBEAT the MultiVehicleManager is notified
    MultiVehicleManager is notifed of the HEARTBEAT and creates a new Vehicle object based on the information in the HEARTBEAT message
    The Vehicle instantiates the plugins which match the vehicle type
    The ParameterLoader associated with the vehicle sends a PARAM_REQUEST_LIST to the vehicle to load params using the parameter protocol
    Once parameter load is complete, the MissionManager associated with the Vehi