Added termPostingsList.java
-a Structure class for storing docID, termFreq(Tf_td), positions[]
Updated GuiEngine, resultWindow to use DiskEngine.java
-Also added a indexReaderWindow and MainMenu window.
IndexWriter.java
-Added sorting of the postings before building the bin files
ProcessQuery.java
-Will automatically detect the appropriate index retrieval method
-Converted everything to arrays that had to deal with posting list 
merges
-Need to test throughly for any bugs with different combinations 
of queries 
DiskPositionalIndex.java
-added a method getPostingsPostion() and getPosition()