SoftRF version MB172

[Moshe Braner]

Now posted to github.  This version introduces significant new functionality.  I've given it some limited testing, on the ground.  If you run into issues, please report them.  Older versions are still on github if you need to revert.

Pawel Jalocha (the person behind the OGN stations and OGN trackers software) has recently introduced dual-protocol reception.  The trick is to leave some of the "sync word" detection to the software.  Now my version of SoftRF can use the same method.  The purpose is to receive both FLARM and ADS-L transmissions simultaneously.  This adds visibility of ADS-L traffic in SoftRF without losing any other functionality.  To turn this on, set the main protocol to "Latest" and the alt protocol to ADS-L.

Moreover, this opens the door for more relaying of traffic data.  FLARMs react badly to "seeing" their own ID, e.g., as a relayed message.  But now SoftRF can relay traffic in the ADS-L protocol, invisible to FLARMs, but visible to SoftRF devices that are using the dual-protocol reception.

Find more information in the "under the hood" document.

A couple of other minor changes in this version:

The frequency for the New Zealand region has been changed from to 869.25 to to 869.20, to follow what FLARMs (other than perhaps some old OZflarms) use.

And added the ability to specify the actual GPIO pin number of altpin0 and ppswire.  This offers more flexibility in unusual setups.