resolve cyclic dependencies in MainWindow collaboration diagram

The Doxygen generated collaboration diagram of class MainWindow reveals the following cyclic dependencies:

• MainWindow has member m_actionManager of type ActionManager which has member m_mainWindow of type MainWindow. - type of m_mainWindow is now QMainWindow
• ProjectDocument::m_linkManager -> LinkInstrumentManager::m_document - LinkInstrumentManager is gone
• MaskContainerModel::maskContainer -> MaskContainerItem::m_model
• JobModel::m_queue_data -> JobQueueData::m_jobModel