Remove IRC support

ENVIRONMENT.rst

@@ -296,9 +296,7 @@ some of this.
   By default peer discovery happens over the clear internet.  Set this
   to non-empty to force peer discovery to be done via the proxy.  This
   might be useful if you are running a Tor service exclusively and
-  wish to keep your IP address private.  **NOTE**: in such a case you
-  should leave **IRC** unset as IRC connections are *always* over the
-  normal internet.
+  wish to keep your IP address private.
 
 * **TOR_PROXY_HOST**
 
@@ -317,8 +315,8 @@ some of this.
 Server Advertising
 ------------------
 
-These environment variables affect how your server is advertised, both
-by peer discovery (if enabled) and IRC (if enabled).
+These environment variables affect how your server is advertised
+by peer discovery (if enabled).
 
 * **REPORT_HOST**
 
@@ -357,27 +355,6 @@ by peer discovery (if enabled) and IRC (if enabled).
   self-signed.
 
 
-IRC
----
-
-Use the following environment variables if you want to advertise
-connectivity on IRC:
-
-* **IRC**
-
-  Set to anything non-empty to advertise on IRC.  ElectrumX connects
-  to IRC over the clear internet, always.
-
-* **IRC_NICK**
-
-  The nick to use when connecting to IRC.  The default is a hash of
-  **REPORT_HOST**.  Either way a prefix will be prepended depending on
-  **COIN** and **NET**.
-
-  If **REPORT_HOST_TOR** is set, an additional connection to IRC
-  happens with '_tor' appended to **IRC_NICK**.
-
-
 Cache
 -----