MEDIUM: stats: support "show info typed" on the CLI

This emits the field positions, names and types. It is more convenient
than the default output for a parser that doesn't know all the fields. It
simply relies on stats_emit_typed_data_field() and stats_emit_field_tags()
added by previous patch for the output. A new stats format flag was added,
STAT_FMT_TYPED, which is set when the "typed" keyword is specified on the
CLI.
diff --git a/include/proto/dumpstats.h b/include/proto/dumpstats.h
index 9080806..ca3357a 100644
--- a/include/proto/dumpstats.h
+++ b/include/proto/dumpstats.h
@@ -29,6 +29,7 @@
 
 /* Flags for applet.ctx.stats.flags */
 #define STAT_FMT_HTML   0x00000001      /* dump the stats in HTML format */
+#define STAT_FMT_TYPED  0x00000002      /* use the typed output format */
 #define STAT_HIDE_DOWN  0x00000008	/* hide 'down' servers in the stats page */
 #define STAT_NO_REFRESH 0x00000010	/* do not automatically refresh the stats page */
 #define STAT_ADMIN      0x00000020	/* indicate a stats admin level */