Changes:
- Merged TX and RX images. You can write this image file onto the SD cards for both RX and TX Raspberries. The devices change their roles accordingly depending on wether a camera is connected or not. In short: Raspberry with camera behaves like a TX device, Raspberry without camera behaves like a RX device.
- Removed message flood to systemd journal of TX to avoid growth of log files. This allows for long running TX devices.