[ArucoThread, FaceRecognitionThread] add signals pushBackgrImage for sending image to update bacground if mSendBackgrImgEnabled is set. Add also slots for setting this variable.
[CoreGraph] add getter form mCameraStream, that will be needed for creating connection to slot updateBackgroungImage().
[FaceRecognitionWindow] add checkboxs and slot for them, that enable/disable sending actual frame from Aruco or FaceDet threads via new added signals. Only 1 thread can send its image for background, but ist independent from image sending to faceDetection window, and that is cool :)
[OpenCVCore] added 4 connections. 2 for sending image from Aruco or FaceDet to mCameraStream from CoreGraph. 2 from FaceRecognitionWindow to this threads for enabling/disabling this image sending. This is the first prototym with  video on background.   TODO: - resizing problem, - bacgroung ratio problem, - automatic disablin camera rotation problem.