Don't crash when intrinsic parameters are not in allowed range
When the values from the intrinsic calibration are not in the allowed range (currently: -5 to 5) PeTrack shuts down with an error message in the console. This message might be overseen by most users. Best would be to display a error box with advice how to resolve this, e.g., more/better images for calibration. When this occurs the "old" calibration should be kept.