- added "select_project" to invoice and po generation
- deletion of invoices and im_trans_invoices now works

  generated PO

  cost_...

- started adding automatic PO generation

- Changed im_cost_items to im_costs
- Started with repeating costs index

  by adding the task_filename to im_trans_tasks in all (two) locations
  where tasks are generated.

However, there are still a log of issues,
in particular the change of invoice and trans_task stati
when creating/deleting invoices

- Fixed creating project directory structure