MEDIUM: stats: add proxy name filtering on the statistic page

This patch adds a "scope" box in the statistics page in order to
display only proxies with a name that contains the requested value.
The scope filter is preserved across all clicks on the page.
diff --git a/include/types/stream_interface.h b/include/types/stream_interface.h
index a808491..2500894 100644
--- a/include/types/stream_interface.h
+++ b/include/types/stream_interface.h
@@ -124,6 +124,8 @@
 				struct proxy *px;
 				struct server *sv;
 				void *l;
+				int scope_str;		/* limit scope to a frontend/backend substring */
+				int scope_len;		/* length of the string above in the buffer */
 				int px_st;		/* STAT_PX_ST* */
 				unsigned int flags;	/* STAT_* */
 				int iid, type, sid;	/* proxy id, type and service id if bounding of stats is enabled */