Reduced Mana Cost Passive

[CollinHerber]

Add a new passive that can be added to the passive tree that reduces the cost of mana by 5% per point, with a max points of 2 per node.

Can add this passive to magic tree for testing purposes for the time being with the decision of 1 passive tree vs multiple still looming

[pilchardheck]

maybe the passive could be called mana efficiency or something