Add a sort option for todo-list

[pled]

Hi,
Thank you for that nice and useful application. I mainly use it for shopping list, using multiple todo-list depending on shops.

It would good to have the option to sort items (for both but mainly for terminated items) so that you can sort them alphabetically.
Doing so, I can more easily retrieve a "terminated" item and uncheck it for a new shopping.

Thank you again.