Pallet Physics Stabilizer

Prevents pallets from sliding unrealistically on regular slopes and improves their stability when placed or stacked.

Unwanted movement is reduced, giving pallets much more natural handling when they are lifted or transported with a forklift.

Changes:
Beta 4: Minor adjustments to sliding behavior and pallet stability.
Beta 3: Improved stabilization when pallets are picked up by forklifts.
Beta 2: Minor fixes.