[MEDIUM] stats: add "show table [<name>]" to dump a stick-table

It is now possible to dump a table's contents with keys, expire,
use count, and various data using the command above on the stats
socket.

"show table" only shows main table stats, while "show table <name>"
dumps table contents, only if the socket level is admin.
diff --git a/include/types/session.h b/include/types/session.h
index 222c30f..f2f15c4 100644
--- a/include/types/session.h
+++ b/include/types/session.h
@@ -231,6 +231,11 @@
 			int bol;		/* pointer to beginning of current line */
 		} errors;
 		struct {
+			void *target;		/* table we want to dump, or NULL for all */
+			struct proxy *proxy;	/* table being currently dumped (first if NULL) */
+			struct stksess *entry;	/* last entry we were trying to dump (or first if NULL) */
+		} table;
+		struct {
 			const char *msg;	/* pointer to a persistent message to be returned in PRINT state */
 		} cli;
 	} data_ctx;				/* used by stats I/O handlers to dump the stats */