Remove many of the translate_words functions, and make several others private. They are a bit of a maintenance pain and aren't a priority for performance improvements anyways

Begin to make the distinction between UTF8 safe and unsafe functions, and implement optimizations when we know the text is ASCII

Switch philosophy so that the utf8 safe version of functions is the default, and the ASCII-only versions are opt-in

Add a generic UTF-8 regular translate function, and use it to power other functions when nightly-features is enabled

An even further performance improvement: we are no longer attempting to support words without vowels