Undo now works, albeit with some limitations: Current framework does not support for more than one subcommand in the List<Subcommand> for any Command. Hence this limits how much undo can do - Undo can only undo ONE action, i.e.

If the user input: add "buy milk" --> edit "buy milk" category "groceries"
Undo can work in this case.
If the user inputs BOTH commands together: add "buy milk" category "groceries"
Undo will not work due to limitations by checkForComponentAmount() inside Command().
Merge branch 'master' of https://github.com/cs2103aug2014-t7-2/main

# By Yui Wei
# Via Yui Wei
* 'master' of https://github.com/cs2103aug2014-t7-2/main:
  cleaned up my test printlns sorry
  cleaned up display to user. (:
  add toPrint method for task
  Today function works now.