cubicweb-jqplot #2961563 csv export: use ';' as default separator instead of tab [validation pending]

as this is what's expected by excel.

prioritynormal
typeenhancement
done in0.4.0
load0.100
load left0.000
closed by#61b4e9561eec csv export: use ';' as default separator instead of tab (closes #2961563)
patch#2961563 csv export: use ';' as default separator instead of tab [applied]