Porter's stemming algorithm for Russian (KOI8-R only)

 Lingua::Stem::Ru applies the Porter Stemming Algorithm to its parameters,
 returning the stemmed words.
 .
 The algorithm is implemented exactly as described in:
 http://snowball.tartarus.org/algorithms/russian/stemmer.html
 .
 The code is carefully crafted to work in conjunction with the Lingua::Stem
 module by Benjamin Franz. This stemmer is also based on the work of Aldo
 Capini, see Lingua::Stem::It.