Implement adding batch of dependencies
Return the correct type for both
Fix lint
Getter for actual task object in subtask and dependencies
Revert back to Task
Update GUI to use my getter
Merge branch 'master' of https://github.com/cs2103aug2014-w10-1c/main into subtask-api

Conflicts:
	You-GUI/main_window.cpp
	You-GUI/task_panel_manager.h
Modify controller
Implement attachment in Model, Serializer, Builder
Implement attachment in GUI
Change to HTML link for demo
Merge branch 'master' of https://github.com/cs2103aug2014-w10-1c/main into subtask-api
Separate basic and advanced tests
Fixes #302 If parent is filtered, don't show the child
Fixes #304 GUI
Add isTopLevel field
Query has too many friend, just make it public
Lint fix
Merge batch deletion to regular deletion
CRD should work with subtasks now