- add w3c validator which is much better than tidy. Validator can be chosen

between w3c and tidy. There is a variable at the end of the file : 
validator_to_use which permit to select the validator.
- enhance error displaying : it's now easier to find the error and correct it
- the two validators could now handle warnings
- now nearly all view pages are tested
- this new version reveal some errors which were not tested before 
  (action which non existing view)


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@19945 20353a03-c40f-0410-a6d1-a30d3c3de9de