feat(util): add (functional) name_map

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>

src/util/name_map.h

@@ -0,0 +1,12 @@
+/*
+Copyright (c) 2014 Microsoft Corporation. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+
+Author: Leonardo de Moura
+*/
+#pragma once
+#include "util/rb_map.h"
+#include "util/name.h"
+namespace lean {
+template<typename T> using name_map = rb_map<name, T, name_quick_cmp>;
+}