erp5_hr_calendar: we need possibility to define start dates on time tables

Calculation of periods needs a starting date to know how to repeat the period.

bt5/erp5_hr_calendar/PortalTypePropertySheetTemplateItem/property_sheet_list.xml

@@ -9,6 +9,7 @@
  </portal_type>
  <portal_type id="Time Table">
   <item>DublinCore</item>
+  <item>Task</item>
  </portal_type>
  <portal_type id="Time Table Line">
   <item>Amount</item>

bt5/erp5_hr_calendar/bt/template_portal_type_property_sheet_list

@@ -5,4 +5,5 @@ Public Holiday | DublinCore
 Time Table Line | Amount
 Time Table Line | SortIndex
 Time Table Line | TimeTableLine
-Time Table | DublinCore
\ No newline at end of file
+Time Table | DublinCore
+Time Table | Task
\ No newline at end of file