The object responsible for hyphenating. It must respond to #hyphenate_to(word, size) or #hyphenate_to(word, size, formatter) and return an array of the word split into two parts; if there is a hyphenation mark to be applied, responsibility belongs to the hyphenator object. The size is the MAXIMUM size permitted, including any hyphenation marks. If the #hyphenate_to method has an arity of 3, the formatter will be provided to the method. This allows the hyphenator to make decisions about the hyphenation based on the formatting rules.