Do not allow inserting duplicated properties with the same per_units, and fix the bug that inserted "empty" properties when unselected (propertyID=-1).
Do not allow inserting duplicated properties with the same per_units, and fix the bug that inserted "empty" properties when unselected (propertyID=-1).

svn path=/trunk/kdeextragear-3/krecipes/; revision=235857

eliovir/krecipes,eliovir/krecipes,eliovir/krecipes,eliovir/krecipes