New Enemy + Early Level Control

Some "good" updates, which hopefully can make the game a bit more "complete"

• New Enemy added: Slugman - Can destroy turrets and are tougher
• Early Level System - Game increases difficulty as you level up. (Some tuning needs to be made)
• Turrets can now be destroyed by Slugman
• Small Indicators below the skills, to show how much power it requires to be activated

Coded this in a hurry for the past 3 hours, hope you can test it out and hopefully have fun as well

Thanks ;)