Add Query and DROPLIST support

New features:

• TAPR TNC2 hardware support and a HAL to allow multiple hardware targets
• Directed ?APRS? query to report on the supported queries
• Directed ?APRSV query support for software version
• Directed ?APRSD query support for stations heard directly during the last 8 hours
• DROPLIST support for up to 10 stations or callsigns with SSID wildcards to enable traffic engineering to drop traffic from or via known problematic stations. Likely also useful to drop traffic chronically coming in from out of area via high level digipeaters with line of sight beyond the APRS LAN.

TAPR TNC2 hardware testing has only been cursory so far thanks to me not having access to an official TAPR TNC2. Testing on a Paccomm Tiny-2 makes it seem like digipeater functionality is parity with the PK-88 platform sans the AM7910 specific features.

Feature rich release for beta testing

Substantially feature complete digipeater firmware replacement for the PK-88 TNC.

New features include:

• APRS queries and sending ACK to all APRS messages sent to the digipeater
• Viscous digipeating for only packets missed by other digipeaters
• Improved logging to avoid packet loss due to high traffic
• Move some config settings to be "shadow" settings since no one should care about them
• Quality of life improvements in the CLI and telemetry systems

Initial 0.1 Release for Field Testing

This is the very first public release of WFDIGI for consumption by others. This firmware has survived several days of testing on my dev digi at home, but I strongly suspect that others will be able to find faults in it, so I would not recommend deploying this at remote radio sites until we get more time under its belt not misbehaving.

This is aiming to be a feature-rich stand-alone digipeater firmware that can be burned to an EPROM and installed in an unmodified AEA PK-88 TNC for APRS digipeater service.
It is not intended to be an I-gate or RF-gate, so no Internet connection or computer is required.

The clean v0.1 firmware build comes up with generic defaults and will refuse to transmit until you configure MYCALL via the serial port at 9600-8n1. The CMOS battery inside the PK-88 will preserve any edits made to the settings across power cycles, but for remote deployments it is also recommended to use a custom build of WFDIGI with the desired settings baked in as the power on defaults by editing /include/config.h and building your own image.

Installing this firmware will require a ROM burner (such as a TL866) and a blank 27C256 or equivalent PROM. If you don't happen to have these capabilities yourself, this is a good thing to ask around for at local radio clubs.