Shadow dancer levels add new spells per day for shadow mage

[garrbear758]

Have a shadow dancer who multiclassed from shadow mage gain more spells per day on shadow dancer levels (similar to pale master)

Shadow mage seems to be a little underpowered with little benefit to make up for the lack of evocation. They also have little synergy with shadow dancer making the combination not worthwhile. I think this would make them a viable choice.