tag: add compatibility with old constructor proto

Signed-off-by: Julien Danjou <julien@danjou.info>

tag.c

@@ -255,7 +255,19 @@ static int
 luaA_tag_new(lua_State *L)
 {
     size_t len;
-    const char *name = luaL_checklstring(L, 2, &len);
+    const char *name;
+
+    if(lua_istable(L, 2))
+    {
+        /* deprecation warning */
+        luaA_warn(L, "%s: This function prototype changed, see API documentation",
+                  __FUNCTION__);
+        lua_getfield(L, 2, "name");
+        name = luaL_checklstring(L, -1, &len);
+    }
+    else
+        name = luaL_checklstring(L, 2, &len);
+
     return luaA_tag_userdata_new(L, tag_new(name, len));
 }