provide for update logging using a file watcher

UpdatePTUDevCtrl/worker.h

@@ -13,6 +13,7 @@
 #include <QThread>
 #include <QByteArray>
 #include <QScopedPointer>
+#include <QFileSystemWatcher>
 
 #include <optional>
 #include <initializer_list>
@@ -522,6 +523,7 @@ private slots:
     bool syncCustomerRepositoryAndFS();
     // bool sendIsmasLastVersionNotification(int progress);
     bool saveLogFile();
+    void onFileChanged(QString const&);
 
 public slots:
     void readyReadStandardOutput();
@@ -535,6 +537,9 @@ private:
 
     QDateTime m_start;
     QByteArray m_standardOutput;
+    QFileSystemWatcher m_fileWatcher;
+    QFile m_updateLog;
+    QFile m_updateLogBackup;
 
     static const QMap<UPDATE_STEP, const char*> smap;