add "ipaccess-telnet" support, i.e. telnetting to an ip.access nanoBTS

There is a special MD5-challenge/response authentication after
establishing the telnet session to an ip.access nanoBTS / TCP port 3210.

The ipaccess-telnet program supports this mode of operation
diff --git a/util/Makefile.am b/util/Makefile.am
index 4500cea..7134d68 100644
--- a/util/Makefile.am
+++ b/util/Makefile.am
@@ -1,6 +1,9 @@
 AM_CFLAGS = -I..
 AM_LDFLAGS = -L..
 
+ipaccess_telnet_SOURCES = telnet-client-ipa.c ../libtelnet.h
+ipaccess_telnet_LDADD = ../libtelnet.la -lssl
+
 telnet_client_SOURCES = telnet-client.c ../libtelnet.h
 telnet_client_LDADD = ../libtelnet.la
 
@@ -10,4 +13,4 @@
 telnet_proxy_SOURCES = telnet-proxy.c ../libtelnet.h
 telnet_proxy_LDADD = ../libtelnet.la
 
-bin_PROGRAMS = telnet-client telnet-chatd telnet-proxy
+bin_PROGRAMS = telnet-client telnet-chatd telnet-proxy ipaccess-telnet