+ add assign2.ngram.NGramNode.java to implement interface assign2.ngram.NGramContainer.java
+ add assign2.ngram.NGramStore.java to implement interface assign2.ngram.NGramMap.java
! update class NGramNode | Finish basic function of this class
! update NGramStore.java | Finish all method basically
! update NGramNode.java toString()
! update NGramStore.java toString()
! update test.java | just for test
+ add NGramNodeTest.java
+ add NGramStoreTest.java
+ add GUI files
! finish basic GUI part
+ add @SuppressWarnings("serial") before class
! Updated 1 Test case
! Updated 1 test case
! update NGramNodeTest.java | began to add some test
! Reverted back to previous version
! Updated 5 JUnit test cases
! update test NGramNode constructor
! Updated 7 testcases for the file NGramNodeTest.java
! Updated 6 testcases for NGramNodeTest.java file along with Javadocs comments
! Updated another 5 testcases to NGramNodeTest.java file
! Updated 6 testcases for NGramStoreTest.java
! Updated 1 testcase for NGramStoreTest.java. Made a few corrections to the previous 6 testcases.
! update NGramNodeTest.java
! update NGramNode.java | Base on test, modify some code
! update NGramGUI.java | refactor CreateGUI method