This allows client applications to locate the IP addresses and the port of
the KISS TCP service, allowing the end user to just select a Dire Wolf from
a list instead of trying to guess its dynamic IP address and typing it in
manually. This is especially convenient on mobile devices.
On Linux, the standard Avahi daemon is used via dbus and the avahi-client
library. Building with it requires installing the development header
package; README.md is updated accordingly.
On Mac, the MacOS dnssd API is used:
https://developer.apple.com/documentation/dnssd?language=objc
I don't have Windows, but more recent Windows 10 builds apparently have
a working DNS-SD mDNS implementation that can be used on 64-bit builds.
'A' uses mark and space filters but simpler and cleaner
than earlier attempts.
New 'B' uses a different technique where the demodulated
signal is proportional to the frequency.