Add a Win32 frontend for xC

This has been more of an exercise.  The performance of Msftedit.dll
is rather abysmal, and its interface isn't the most accomodating.

That said, the frontend is quite usable, at least on Windows 10+.

README.adoc

@@ -2,7 +2,7 @@ xK
 ==
 
 'xK' (chat kit) is an IRC software suite consisting of a daemon, bot, terminal
-client, and a web frontend for the client.  It's all you're ever going to
+client, and web + Win32 frontends for the client.  It's all you're ever going to
 need for chatting, so long as you can make do with slightly minimalist software.
 
 They're all lean on dependencies, and offer a maximally permissive licence.
@@ -137,6 +137,16 @@ For remote use, it's recommended to put 'xP' behind a reverse proxy, with TLS,
 and some form of HTTP authentication.  Pass the external URL of the WebSocket
 endpoint as the third command line argument in this case.
 
+xW
+~~
+The Win32 frontend is a separate CMake subproject that should be compiled
+using MinGW-w64.  In order to run it, make a shortcut for the executable and
+include the relay address in its _Target_ field:
+
+ C:\...\xW.exe 127.0.0.1 9000
+
+It works reasonably well starting with Windows 7.
+
 Client Certificates
 -------------------
 'xC' will use the SASL EXTERNAL method to authenticate using the TLS client