Compute probabilities in N-grams model for tags in UD format

Usage
===========
  - bigram  : function for bigrams with specify tag
  - trigram : function for trigrams with specify tag
  - ngram   : general function for ngram with specify tag

##### ngram matriz funcions
  - bigram_matrizs	: matriz with bigram probabilities for tags
  - ngram_matriz	: matriz with ngram probabilities for tags