WWIV 5.7.1 Preview release

We are happy to announce a prerelease (aka release candidate, tech preview) of WWIV 5.7 for Linux, Windows, and OS/2.

WWIV 5.7 is the 7th major release after the long-awaited 5.0 release and in addition to native
WWIVnet support (no more DOS dependencies) on all platforms, supports native Fido Technology
Networking (FTN) Support and fully customizable menus.

System Requirements:

Win32: Windows 7 or later using MS Visual C++ 2019 Community Edition.
Linux: GCC 8.3 (or later) on (Debian10, Centos7 with SCL, or Ubuntu 20.04)
OS/2: Warp 4, ArcaOS 5.0 or newer.
CMake 3.13 or newer

Title	Link
Main Web Site	https://www.wwivbbs.org
Documentation	http://docs.wwivbbs.org
Code	http://github.com/wwivbbs/wwiv

Upgrade notes.

Please read upgrade.txt in the distribution for more specific upgrade notes from 5.6

New Features/Changes

+ Telnet support from wwivd.  Use @telnet:HOST:PORT for the telnet command
  in the wwivd matrix setting for that BBS entry.
    ┌─────────────────────────────────────────────── Matrix Config: mystic ┐
    │            Key: m                                                    │
    │           Name: mystic                                               │
    │    Description: Mystic BBS (MIS)                                     │
    │    Working Dir:                                                      │
    │ Telnet Command: @telnet:localhost:2300                               │
    │    SSH Command:                                                      │
    │   Require Ansi: No                                                   │
    │     Start Node: 1                                                    │
    │       End Node: 10                                                   │
    │     Local Node: 0                                                    │
    └──────────────────────────────────────────────────────────────────────┘
+ Added scripts for using QEMU online.  Tested DOS doors under QEMU/FreeDos
  on Linux.
+ WWIV builds on OS/2 under GCC 9.2.
* Incorrect BY: line when posting to a Fido sub (#1460)
* Don't let a sub go to position 0 (#1457)
* regions and zip-city not unzipped with default install on linux (#1455)
+ STDIO support now works on Win32. It works when WWIV is using either
  sockets or pipes to talk to wwivd.
+ Included WWIVFOSS which will convert FOSSIL into Named Pipe calls for telnet
  ability from WWIVd.
  * Use -XP for (PIPE) instead of -XS or -XT to use it.  -H is obsolete
    when using PIPE since the pipe name is hard coded to be
    \\.\PIPE\WWIV# and \\.\PIPE\WWIV#C where # is the node number.  
+ WWIVFOSS is now bundled with the OS/2 cpack target.
+ WWIV supports listening on either a TCP local socket port or an UNIX
  socket for the door to connect back to instead of using socket passing
  ala DOOR32 style.  This works on both Windows and UNIX.  Please note that
  Windows 10 17063 or later is needed for AF_UNIX support on Windows.
  This is handy for using QEMU from within BBS to run DOS based doors.  
  The port number or socket path will be available as a new (%Z) replacable
  parameter from chainedit when using the selected chain execution mode.