Use TodoItem class instead of strings to represent items, so we can store them in a SQLite database instead of a plaintext file.
Added dummy UI for enabling/disabling due dates, not functional yet.
Added restriction to only use in portrait mode due to the space constraints of the layout.
Added support for defining, editing, and saving due dates in the edit activity.
Display due dates in the list view.
Created dummy edit item dialog to replace the edit activity. passed information into the dialog, but no edits are saved yet.
Added save functionality to edit dialog.
Removed code having to do with the edit activity since the dialog has now completely replaced the activity. Yay.