Added tower upgrades and began working on main menu!

Devlog #5 for Evolution game
So this time I finally added the tree/towers upgrades, which took a hellish time to implement, but it works now, hey?
Outside that I also added all of the worlds for the game, so now they’re complete. I also added a small settable cooldown between worlds, so it does not feel so instant and sudden. Many enemies have been added as well. And I also added all of the three trees and their stages.
To top it all off I also added range for towers, just forgot to log these changes, so they’re now all in this one big chunk together.