Function open_utf8 

pub fn open_utf8(state: &mut LuaState) -> Result<usize, LuaError>

Open the utf8 library.

Registers all functions from FUNCS into a new table, then sets utf8.charpattern to the byte-string pattern matching one UTF-8 sequence.

C: LUAMOD_API int luaopen_utf8(lua_State *L)