Skill Tree

• New skill tree! Buy skills with bubble gums, they spawn every now and then in trash
• Reworked upgrades list
• Reworked rats AI to be more efficient
• Trash sells instantly now instead of waiting the recycle car 
• Rebalanced all cost and value of upgrades

and much more

Saves didn't persist with the old save system but it now works with this new build and future builds :p