Todo List Panel

[kilbouri]

A basic todo-list component should exist. The component should be compatible with the paneling system. The todo list should support addition and removal of list items, as well as marking an item as completed. The list should support rendering of nested items. Creation of nested items at this time is not required.

Non-goals for this issue:

1. Server storage of the todo list
2. Drag-and-drop re-ordering of list items

[kilbouri]

@rdrpenguin04 please push your local dev branch and link it to this issue :)