Allow UPnP mapping when USE_UPNP is defined and miniupnpc is installed at build time(statically linked).

Thanks joepie91 for the translation of the new copyright notices into Dutch.
Thanks sipa for the translation of the new copyright notices into French.
Thanks megu for the translation of the new copyright notices into Spanish.
Thanks justmoon/Blitzboom for the translation of the new copyright notices into German.
Thanks Joozero for the translation of the new copyright notices into Italian.
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build-unix.txt

@@ -3,7 +3,8 @@ Distributed under the MIT/X11 software license, see the accompanying
 file license.txt or http://www.opensource.org/licenses/mit-license.php.
 This product includes software developed by the OpenSSL Project for use in
 the OpenSSL Toolkit (http://www.openssl.org/).  This product includes
-cryptographic software written by Eric Young (eay@cryptsoft.com).
+cryptographic software written by Eric Young (eay@cryptsoft.com) and UPnP
+software written by Thomas Bernard.
 
 
 UNIX BUILD NOTES
@@ -36,10 +37,15 @@ You need to download wxWidgets from http://www.wxwidgets.org/downloads/
 and build it yourself.  See the build instructions and configure parameters
 below.
 
+Requires miniupnpc for UPnP port mapping.  To compile with UPnP support,
+install miniupnpc and compile after setting USE_UPNP.  It can be downloaded
+from http://miniupnp.tuxfamily.org/files/.  
+
 Licenses of statically linked libraries:
 wxWidgets      LGPL 2.1 with very liberal exceptions
 Berkeley DB    New BSD license with additional requirement that linked software must be free open source
 Boost          MIT-like license
+miniupnpc      New (3-clause) BSD license
 
 Versions used in this release:
 GCC          4.3.3
@@ -47,6 +53,7 @@ OpenSSL      0.9.8g
 wxWidgets    2.9.0
 Berkeley DB  4.7.25.NC
 Boost        1.37
+miniupnpc    1.5
 
 
 Notes
@@ -73,6 +80,15 @@ make install
 ldconfig
 
 
+miniupnpc
+---------
+tar -xzvf miniupnpc-1.5.tar.gz
+cd miniupnpc-1.5
+make
+sudo su
+make install
+
+
 Berkeley DB
 -----------
 You need Berkeley DB 4.7.  Don't use 4.8, the database/log0000* files