* implement WAV file writing
* implement stereo pilot pulse-per-second
* implement RDS decoding
* figure out why we sometimes lose stereo lock
* it looks like IF level sometimes varies so much that it saturates the receiver; perhaps this can be solved by dynamically managing the hardware gain in response to level measurements
* investigate problem at low IF sample rates; it seems that librtlsdr is not telling the truth about the actual sample rate.
* figure out if I/Q balance can improve weak stations
* figure out if hardware gain settings can improve weak stations
* consider FM demodulation with PLL instead of phase discriminator