Added the ability to 'Undo mark all as done' todos marked as complete with 'Mark all as done'
in the 'Todo' tab of the Todo dashboard.
The operation undos only the todo previously marked as done with the 'Mark al as done' button.
The Done button will change to an Undo button and the line item will be greyed out.
Bold links will be unbolded.
The user can undo the task by clicking the Undo button.
