Support “i18n” feature

[KarliosQu]

Hello, I've noticed that more and more developers from different countries are starting to use Rust , and playground has been a very reliable, safe and convenient way to try and sharing code among people. Therefore I was wondering if there are any plans to add internationalization (i18n) features to playground? If yes, I will happily help, try to contribute this feature, and providing some Chinese translation.