Revert "Revert "Sliding Gate/Wall Script""

This reverts commit 2469bb8bd5b57d226ad33d44b1f7c6f8997a6a6f.

Revert "Sliding Gate/Wall Script"

This reverts commit
e338a5c2c5a21879183846e24f5ff1670e780d3d.

Sliding Gate/Wall Script

Updated Gate script to make the attached
obstacle slide out of the way
when powered, and slide back when
unpowered.  The wall will currently
not collide with gears, but it does
collide with other wall objects.
Also there's still a bug with the gear
getting 'powered' when dragging a
gear over the obstacle's source gear.