message: Support software triggering aravis cameras
  If an aravis camera is software triggered, a trigger needs to be explicitly sent using `arv_camera_software_trigger`, otherwise the camera will not grab any frames.
diff: @@ -148,6 +148,7 @@ protected:
  double exposureCompensation;
  bool autoGain;
  double targetGrey; // Target grey value (mid grey))
  + bool softwareTriggered; // Flag if the camera is software triggered
  gint64 *pixelFormats;
  guint pixelFormatsCnt;
  @@ -275,6 +276,7 @@ bool CvCaptureCAM_Aravis::open( int index )
  exposure = exposureAvailable ? arv_camera_get_exposure_time(camera) : 0;
  gain = gainAvailable ? arv_camera_get_gain(camera) : 0;
  fps = arv_camera_get_frame_rate(camera);
  + softwareTriggered = (strcmp(arv_camera_get_trigger_source(camera), "Software") == 0);
  return startCapture();
  }
  @@ -290,6 +292,9 @@ bool CvCaptureCAM_Aravis::grabFrame()
  ArvBuffer *arv_buffer = NULL;
  int max_tries = 10;
  int tries = 0;
  + if (softwareTriggered) {
  + arv_camera_software_trigger (camera);
  + }
  for(; tries < max_tries; tries ++) {
  arv_buffer = arv_stream_timeout_pop_buffer (stream, 200000);
  if (arv_buffer != NULL && arv_buffer_get_status (arv_buffer) != ARV_BUFFER_STATUS_SUCCESS) {
  