Build 9: boost, easier item drops, some juice

What’s new:

• You can now boost with Shift if you wanna go faster
• Dropping items no longer requires pressing E, just stop accelerating (W) to drop off the current item at the drop zone.
• All item spawns are now timer based, the game spawns new items until there are 3 items on the ground
• Item spawn positions are more spaced out (and can no longer spawn on top of each other)
• Item spawn and disappear with Z tweens (from / to underground)
• Picked up items gradually move to their trailer (this needs improvement, but it’s better then nothing)
• Picked up items now rotate with the trucks
• Added first sound: the truck’s engine