Fix lupdate issues

- missing Q_DECLARE_TR_FUNCTIONS
- some full qualifications needed for confused lupdate
- avoid breaking some translations from former TaskListPlugin,
  VcsCommand and highlighter settings refactoring

Change-Id: Ia3b34095512a7bad6903f0aff6095313ee39e3e4
Reviewed-by: hjk <hjk@qt.io>

src/plugins/projectexplorer/taskfile.h

@@ -20,6 +20,7 @@ public:
 
 class TaskFile : public Core::IDocument
 {
+    Q_DECLARE_TR_FUNCTIONS(TaskList::Internal::TaskListPlugin)
 public:
     TaskFile(QObject *parent);