* call _delObject before changing the id of the object we are deleting in
 setCellRange (similar to r26610)

tests/testXMLMatrix.py:
 * creates cells in the test before testing setCellRange, to make sure that it
 works with existing cells.
 * use LogInterceptor to make sure there are no error logged. This shows that
 we get duplicate uids if we don't have portal_activities, but i'm not sure
 this is a real problem, is ERP5 supposed to work without portal_activities ?



git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@27576 20353a03-c40f-0410-a6d1-a30d3c3de9de