Improve CategoryTool buildSQLSelector result pertinence: when searching for...

Improve CategoryTool buildSQLSelector result pertinence: when searching for documents matching categories, use a left join instead of a succession of "OR".
This is implemented in a new method, with the possibility to fallback to original behaviour.
Original method now just calls the new one in compatibility mode.


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@22163 20353a03-c40f-0410-a6d1-a30d3c3de9de