Patch 2.4.0: Unit buffs, spell powerup buffs and new achievements

[b]Unit buffs:[/b] Cultists from 6 to 8 damage. Priests from 7 to 9 damage. Cherubs passive heal from 10 to 15 health regenerated every 2 seconds. [b]Spell powerup buffs:[/b] Spell damage powerup from +13% to +20% per rank. Healing powerup from +17% to +30% per rank. [b]New achievements:[/b] Each mage now has two new achievements (In total 20 new achievements): 1: Survive arena endgame round 5 on impossible or harder with each mage. 2: Survive arena endgame round 5 on +475% with each mage.