It can be useful to know which activity a person is currently related to in his career. This is useful both for sorting people and to enter people without a company (ex. consultants) yet associate them to an activity.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@15650 20353a03-c40f-0410-a6d1-a30d3c3de9de