Added logic to add the company_contact_id if not explicitely set

  Updated to OpenACS 5.7

  Extending the default end-date by 15 days
  so that the current month is always included

  Fixed issue _showing_ billable hours for projects
  without tasks. The invoice generation was OK, but
  the invoiced hours are not shown.

- changed version numbers

	- Disabling "tax" field if not desired
	- Implemented material_id in im_invoice_lines

	- Implemented company-wide bank holidays
	- Extended invoices to check the CostCenter before
	  creating an invoice
	- Implemented custom number circuits for EconoMedic
	- Implemented controlling by day
	- Implemented invoicing by day
	- Implemented conversion function from hours to days,
	  limiting the number of days logged per consultant
	  to 1.
	- Implemented OpenOffice invoicing templates
	- Implemented Template maintenance page in /intranet/admin/
	- Improved filtering in AbsenceListPage

- Fixed issue with invoice_hour_type error during timesheet invoicing