Aura Magic

1) updated the magic spell models and images and add 3 other types

2) Added a new Block Magic Spell

  a) Primary attack is the same but primary charge creates magic stairs that disappear after a while

  b) Secondary charge makes similar magic blocks but they are flat going forward (for bridging gaps)

3) Added 5 prefabs that have a 1/6 chance to spawn instead of the normal crystals, they contain lots of gems and crystals so worth going for.

4) Some adjustments to costs of spells and then adjusted the shield life time so it lasts 3 times as long