Add support for localization files

[Nevakanezah]

The plugin is currently implemented with reams of hardcoded text values all over the place, especially in the registration process where it's a big pain to change.

Refactor the code so that all player-facing text pulls from a localization file defined in the config, and add a localization folder to contain these (probably KVG) files.
This would allow server admins to localize the plugin in any manner they like, and improve accessibility.

[Nevakanezah]

Some of this work has already been implemented by Chloe; complete implementation is pushed to a future release