Pass mg_http_message to MG_EV_WS_OPEN

src/event.h

@@ -27,9 +27,9 @@ enum {
   MG_EV_WRITE,      // Data written to socket       int *num_bytes_written
   MG_EV_CLOSE,      // Connection closed            NULL
   MG_EV_HTTP_MSG,   // HTTP request/response        struct mg_http_message *
-  MG_EV_WS_OPEN,    // Websocket handshake done     NULL
-  MG_EV_WS_MSG,     // Websocket message received   struct mg_ws_message *
-  MG_EV_WS_CTL,     // Websocket control message    struct mg_ws_message *
+  MG_EV_WS_OPEN,    // Websocket handshake done     struct mg_http_message *
+  MG_EV_WS_MSG,     // Websocket msg, text or bin   struct mg_ws_message *
+  MG_EV_WS_CTL,     // Websocket control msg        struct mg_ws_message *
   MG_EV_MQTT_CMD,   // MQTT low-level command       struct mg_mqtt_message *
   MG_EV_MQTT_MSG,   // MQTT PUBLISH received        struct mg_mqtt_message *
   MG_EV_MQTT_OPEN,  // MQTT CONNACK received        int *connack_status_code