Update translations so there's a fallback available without loading translation files. #682

Right now, if the translation files can't be loaded, the entire player falls back to a native player.

This is excessively fragile. There should be a default language that's loaded by default.

A few possible options:

• Add en.json as an object declared directly in getTranslationText() to ensure it's always available.
• Add a fallback string in all calls to text. This means changing this.tt to be a method, instead of a property, so that a fallback argument can be passed.

The second is a lot of work, but has the advantage that you can more easily tell what the relevant text is when editing code in context.