1. modified MyController to suit edit function. ie: when the user type "edit 2" the program will append the task corresponding to 2 into the input box.
2. Added EditListener.java. This class implements ChangeListener. This file is needed for implementation of the edit function.
1. added the method move in Both CommandGenerator and TaskManager. Now user can move a task to another task location.
for example, if you type "move  1 2", task 1 will be moved to task 2.
Revamp of structure.