Course Number: 600.120
section number: 2
semester: fall 2016
assignment number: 7
Coco(Xiaoyan) Li, xli152

What the program does:
     This program takes in a list of files and create a model of ngrams(depending on user input n), then either print out the model or output generated phrases according to this model. It also includes catch unit testing program.

     **make N in Makefile make the unittest for NgramCollection

Source files:
       NgramCollection.cpp: contains functions toString() that converts the model into printable strings in alphabetacal, reverse alphabetable or by count orders. It also includes increment(), helper function to makemodel(), and pickWord(), helper function to generate() function that makes the model.
       LanguageModel.cpp: contains readinfile() function, function that reads in all the files given in the input file, and also makemodel(), which creates a model of Ngrams of all the files read in. 
       unitTests-NgramCollection.cpp: unit testing for NgramCollection.cpp
       unitTests-LanguageModel.cpp: unit testing for LanguageModel.cpp