Remove method for delete index
added some functionality to commandSort
added display function
Edited parseEndTime
Added test case for end time
Edited parse start time
added test time
changed the commands so that execute and undo returns String
search for feedback completed
Merge branch 'master' into vani's_branch

Conflicts:
	src/todologApp/CommandAdd.java
	src/todologApp/CommandDelete.java
	src/todologApp/CommandSearch.java
	src/todologApp/CommandSort.java
Merge remote-tracking branch 'origin/master' into Stanley's_Branch

Conflicts:
	src/todologApp/Task.java
added command done
Added Command Display
added display tasktype
minor changes in add delete and edit
written functionality for markAsDone command
Merge 'Stanley's into linh-dev

Conflicts:
	src/todologApp/Task.java
Merge branch 'vani's_branch' into linh-dev