To be done !
Just a word on WBS
WBS stands for "Work Breakdown Structure". It's a key to classify your tasks.
In current version (0.0.7) it is used only to sort tasks. If you leave it blank,
tasks are sorted according to their number.
Warning: it is a STRING sort. "10" is smaller than "2". Use "02" instead to get the correct order.
Future versions will allow to filter tasks on their WBS.