#587: fixed
#587: added correct resizing after resizing of mainwindow
#589: added context menu for employee nodes
#589: added constants for warning messages
#589: fixed error with objects clearing
#589: added different context menus
#589: completed different context menu for scene and nodes
#589: fixed AddObjectDialog
#589: fixed ChangeObjectDialog
#589: fixed DeleteObjectDialog
#589: fixed
#586: fixed tests build
#588: fixed