Updated Slovenian translations

issue3379
review1092002
Fix value of Reference fields when id is -1

issue3375
review1089002
merge
Fix Reference widget when no model is selected, value is just text

issue3352
review1090002
Block button handler instead of deactivate button

By deactivating the button, the button lost the focus which makes NoModal
selects the wrong sensitive widget and thus the wizard behaves like if it was
launched from the menu instead of from a tab.

issue3353
review1083003