Replace lua_ref(st,TRUE) by luaL_ref(st, LUA_REGISTRYINDEX)
Replace lua_ref(st,TRUE) by luaL_ref(st, LUA_REGISTRYINDEX)

Both expressions are equivalent in Lua 5.1 by definition and Lua 5.2
does not include lua_ref anymore.

jsbackus/notion-libextl,jsbackus/notion-libextl