Upgrade tree and lots of small bug fixes

Here are some things that were added:

• added rounds
• fixed match ending bug
• fixed many menu bugs (cursor locking when it shouldn't, not being able to buy in countdown...)
• added upgrade tree system
• added upgrade points
• added game reset at end
• added upgrade levels
• cleaned up some code
• added auto-ready that triggers when you have no points left
• disabled wall running (will prob be an upgrade later)

Here are all of the upgrades that have been added so far:

• health
• speed
• damage
• regen
• dash
• extra jump
• headshot multiplier
• firerate