Document the bare-JID-for-IRC-users feature

INSTALL

@@ -4,18 +4,28 @@
 
 Build and runtime dependencies:
 
+
 Libraries:
+
 - crypto++
  Sometimes packaged as cryptopp.  This library is used to generate MD5
  hashes.
  http://www.cryptopp.com/
+
 - expat
  Used to parse XML from the XMPP server.
  http://expat.sourceforge.net/
+
 - libiconv
  Encoding from anything into UTF-8
  http://www.gnu.org/software/libiconv/
 
+- libidn (optionnal, but recommended)
+ Provides the stringprep functionality. Without it, JIDs for IRC users are
+ not provided.
+ http://www.gnu.org/software/libidn/
+
+
 Tools:
 - A C++11 compiler.
 - CMake

doc/biboumi.1

@@ -52,7 +52,7 @@ IRC channels and IRC users JIDs have a localpart formed like this: \fBname\fR, t
 For an IRC channel, the name starts with \fB\'&\'\fR, \fB\'#\'\fR, \fB\'+\'\fR or \fB\'!\'\fR\. Some other gateway implementations, as well as some IRC clients, do not require them to be started by one of these characters, adding an implicit \fB\'#\'\fR in that case\. Biboumi does not do that because this gets confusing when trying to understand the difference between \fIfoo\fR, \fI#foo\fR, and \fI##foo\fR\.
 .
 .P
-If the name starts with any other character, this represents an IRC user\.
+If the name starts with any other character, this represents an IRC user\. If compiled with Libidn, an IRC user has a bare JID representing the “hostname” provided by the IRC server\.
 .
 .SS "Join an IRC channel"
 To join an IRC channel \fB#foo\fR on the IRC server \fBirc\.example\.com\fR, join the XMPP MUC \fB#foo%irc\.example\.com@hostname\fR\.

doc/biboumi.md

@@ -80,6 +80,8 @@ this gets confusing when trying to understand the difference between
 *foo*, *#foo*, and *##foo*.
 
 If the name starts with any other character, this represents an IRC user.
+If compiled with Libidn, an IRC user has a bare JID representing the
+“hostname” provided by the IRC server.
 
 ### Join an IRC channel