Hotfix 0.5.1

Small hotfix and slight feature update.

Fixes:

• Putting two of an item into the cart and removing both no longer increases the amount of items needed.
• Fixed some of the computers not being counted when put in the cart.

New features:

• New music volume slider in settings screen
• You can now double-click "R" to restart the game
• Fixed up the map a bit to make it more navigateable + less empty