Start X11 and web frontends for xC

For this, we needed a wire protocol.  After surveying available options,
it was decided to implement an XDR-like protocol code generator
in portable AWK.  It now has two backends, per each of:

 - xF, the X11 frontend, is in C, and is meant to be the primary
   user interface in the future.

 - xP, the web frontend, relies on a protocol proxy written in Go,
   and is meant for use on-the-go (no pun intended).

They are very much work-in-progress proofs of concept right now,
and the relay protocol is certain to change.

NEWS

@@ -1,5 +1,9 @@
 Unreleased
 
+ * xD: implemented WALLOPS, choosing to make it target even non-operators
+
+ * xC: made it show WALLOPS messages, as PRIVMSG for the server buffer
+
  * xC: all behaviour.* configuration options have been renamed to general.*,
    with the exception of editor_command/editor, backlog_helper/pager,
    and backlog_helper_strip_formatting/pager_strip_formatting
@@ -10,11 +14,13 @@ Unreleased
 
  * xC: normalized editline's history behaviour, making it a viable frontend
 
- * xC: made it show WALLOPS messages, as PRIVMSG for the server buffer
-
  * xC: various bugfixes
 
- * xD: implemented WALLOPS, choosing to make it target even non-operators
+ * xC: added a relay interface, enabled through the general.relay_bind option
+
+ * Added an experimental X11 frontend for xC called xF
+
+ * Added an experimental web frontend for xC called xP
 
 
 1.5.0 (2021-12-21) "The Show Must Go On"