`Romaji` is a converter library to romanize Japanese hiragana/katakana string by standard and IME typing style.
Even though [icu::Transliterator](http://userguide.icu-project.org/transforms/general) already has provided the same functions, and returns only one romanized string.
However, there exists several different romanization systems, so one hiragana/katakana string has so many romanize string.
For example, `"ちゃ"` can be romanized as `"cha"`, `"tya"`, `"chixya"`, `"tixya"`, `"chilya"`, or `"tilya"`.
`Romaji` provides romanized strings as many as possible.
If an input string contained non hiragana/katakana characters (includes kanji), `Romaji` return the characters as same as the input.
For example, `Romaji` converts the input `"お茶の水"` to `"o茶no水"`.
The mapping from hiragana/katakana to romaji is based on common IME's system to type Japanese on a computer.
Therefor, `Romaji` does not directly implement the standard system like Hepburn, Nihon-shiki or Kunrei-shiki, but includes them.