CA factorial map, when a label is highlighted (mouse over or click event), other point labels are drawn over it
When a label is highlighted (mouse over or click event), the other not
highlighted labels of same series (rows or columns) must be drawn before
the highlighted label(s).
At this moment, they are drawn over the highlighted label(s) making the
functionality very less useful.
MD : OK for Ubuntu 14.04 and Windows XP
(from redmine: issue id 1257, created on 2015/02/19 by Sebastien Jacquot)