More turrets!

Hello fans,

The remaining three turret-models are done but I still need to program them and add all 4 turrets to the save game. 

1. Slow single shots, high damage, high durability and high costs
2. Slower single shots, explosion, very high area damage, very high durability and very high costs
3. very fast single shots, high damage, extreme durability, extreme costs

Have a nice day