unit test cases for add, delete, display and clear methods are revised, displayTextList method is updated
unit test cases for add, delete, display and clear methods are revised, unit test for testSortTextList is updated
all test cases for add, delete, display, clear and sort methods revised, sort method implemented
two more test cases added to testSortTextList
unit test cases revised, three new test cases for search method added
searchText method implemented, unit test cases for searchText method are revised