efficient XS-Based n-gram spectrum analysis module

 n-Gram analysis is a field in textual analysis which uses sliding window
 character sequences in order to aid topic analysis, language
 determination and so on. The n-gram spectrum of a document can be used
 to compare and filter documents in multiple languages, prepare word
 prediction networks, and perform spelling correction.
 .
 Text::Ngram provides an efficient XS-based implementation of n-gram
 spectrum analysis.