Patch 0.29d: Fixed spell bugs and nerfed summon spellls

Patch 0.29d:
- Fixed a bug causing you to not get your 8th spell when buying it.
- Fixed a bug with Healing Wave +2 units hit upgrade, causing it to have no effect (the units hit always stayed at 8 before).
- Summon melee and ranged spells from 20 to 25 sec cooldown.