[MEDIUM] split fe->maxconn into fe->maxconn and be->fullconn

The maxconn argument is used only for the listeners, and the
fullconn is used only for the backends. If unset, it inherits
maxconn's value which itself can inherit the default or the
global value (we might need to change this).
diff --git a/include/types/proxy.h b/include/types/proxy.h
index 8480143..8aaa3a7 100644
--- a/include/types/proxy.h
+++ b/include/types/proxy.h
@@ -98,7 +98,8 @@
 	unsigned int feconn, feconn_max;	/* # of active frontend sessions */
 	unsigned int beconn, beconn_max;	/* # of active backend sessions */
 	unsigned int cum_feconn, cum_beconn;	/* cumulated number of processed sessions */
-	unsigned int maxconn;			/* max # of active sessions */
+	unsigned int maxconn;			/* max # of active sessions on the frontend */
+	unsigned int fullconn;			/* #conns on backend above which servers are used at full load */
 	unsigned failed_conns, failed_resp;	/* failed connect() and responses */
 	unsigned failed_secu;			/* blocked responses because of security concerns */
 	int conn_retries;			/* maximum number of connect retries */