WSPR decoder, config improvements, sample IQ files

[jks-prv]

1. SDR hardware selection via a single parameter called “SDR_source”.
2. New parameter “waterfall_auto_adjust” allows initial adjustment.
3. Added an example IQ file from the 2005 CQWW CW contest. It’s adds an additional 4 MB to the 9 MB of the repository, so that needs to be considered. But it may be useful to future porting efforts.

[jks-prv]

Updated pull to include a WSPR secondary demodulator. For now only works with the supplied demo IQ sample file. Needs a little more work to support arbitrary sample rate IQ sources (e.g. RTL-SDR)