added i18n.get(namespace, key, data)
added i18n.fill(namespace, key_attr)
fix for nonstandard namespaces
shorter i18n.get()
let top-level be functions as well

NOTE: assumes conditional access, e.g. with i18n.get()
added support for positional args, with new tests
fixed i18n.get() to accept empty strings
added support for empty string as plural/select key value, using ''{}