Initial Zombie Wave System, plus more.

My initial foray into a wave system.

Many ideas are in place, but have yet to be tested.

Ideas include:
Difficulty modifier: Health and EXP increases with time.
Level modifier: Levels and SkillPoints are not earned linearly.

The turret can be placed in front of Zed the same way the bullet is
spawned in front of Zed.

The gameStateController is made to manage the wave system. ZombieWave is
also implemented as a container for ZombieSpawnJobs.

The *problem* is that Unity hangs when handleSpawnJobs is reached. I
suspect it has to do with the spawnJobs not being set correctly. I will
fix it with future update.
Zombie Wave System working.

The problem lay in my wave being referenced before it could be created.
Since Unity doesn't give any indications to which script is called
first, you have to enforce referencing to happen at the End of the
frame. So yeah, that's been fixed.

Skill points will increase in step with levels. Experience points have
been added too. I can continue to improve the leveling system with time,
but for now I think we have a good system going for us.