Implement task list indices from 1.
Merge pull request #364 from lowjoel/tasks-from-index-1

Implement task list indices from 1 (Controller's side)
Merge branch 'master' of https://github.com/cs2103aug2014-w10-1c/main into fix-subtask-display-bug
GUI refreshes task panel after Edit command.
Controller shouldn't know what the default filter is, hide it by API
Fix compiler warnings
Implement Delta for UpdateTask
Finish delta
Fix lint