FTL resources leak memory on exit

```
ERROR: 2 resources still in use at exit.
   at: ResourceCache::clear (core\io\resource.cpp:609)
Resource still in use: res://i18n/en.ftl ()
Resource still in use: res://i18n/de.ftl ()
```

When closing [ChatLane](https://github.com/RedMser/chatlane).

Translations are loaded via an autoload that does `TranslationServer.add_translation(load(...))`