add a new option to display all the occurences of the word (if the word is three times in a file, display 3 lines)
This behavior is enable by default but can be disable by passing parameter first_occurence=1 to the external method


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@25987 20353a03-c40f-0410-a6d1-a30d3c3de9de