Add new functions
Add new functions

Several big changes with this commit:

* The updateTodoList() and updateDoneList() are created.
* These functions are called whenever:
    - an item is clicked
    - a button is clicked
    - items are re-ordered
* Clicking on the "Delete all" button now really deletes tasks instead of
simply hiding them.

pwizla/tinysteps-todolist,pwizla/tinysteps-todolist