MINOR: dict: Add dictionary new data structure.

This patch adds minimalistic definitions to implement dictionary new data structure
which is an ebtree of ebpt_node structs with strings as keys. Note that this has nothing
to see with real dictionary data structure (maps of keys in association with values).
diff --git a/include/proto/dict.h b/include/proto/dict.h
new file mode 100644
index 0000000..26f48de
--- /dev/null
+++ b/include/proto/dict.h
@@ -0,0 +1,9 @@
+#ifndef _PROTO_DICT_H
+#define _PROTO_DICT_H
+
+#include <types/dict.h>
+
+struct dict *new_dict(const char *name);
+struct dict_entry *dict_insert(struct dict *d, char *str);
+
+#endif  /* _PROTO_DICT_H */