fix in-/decreasing of date/time values in ikhal's editor
fix in-/decreasing of date/time values in ikhal's editor

sdx23/khal,pimutils/khal,pdav/khal,geier/khal,dzoep/khal,hobarrera/khal,sheeprine/khal,sithglan/khal,sithglan/khal,sheeprine/khal