properties :
- added method setPropertyList
- make getPropertyList working on a mono valued property. It will
  return a list of one element (the value of the property)
- make setPropertyList working on a mono valued property, in such
  case a list of one element must be given
- do not generate List methods for mono valued properties any more. 
  List methods were generated for mono valued properties only when 
  some acquisition parameters were defined
- add unit test for getPropertyList and setPropertyList


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@25485 20353a03-c40f-0410-a6d1-a30d3c3de9de