* Improve furigana when reading kana is not an exact match
* Simplify group structure
* Return consistent type
* Add more tests
* Remove redundant isAmbiguous assignment
* Simplify group usage
* Add helper function
* Optimize returned arrays
* Use variable
* Remove s(p)lice calls
* Reduce number of convertKatakanaToHiragana calls
* Optimize text length access
* Optimize reading substring
* Move segmentize to a separate function
* Use var
* Use _createFuriganaSegment
* Optimize distributeFuriganaInflected