Allow for localized strings in configuration files

Implement a syntax to allow for localized strings in configuration files, e.g.

    ServerMOTD="foo"
    ServerMOTD[fr]="bar"

`str[x]` will then be used instead of `str` if the locale is `x`.

All strings (including localizations) can be sent between server and client; the client uses its own locale when deciding which string to display.