Test Pad 0.6.0

Updates to help stress test offroad suspension.


- Thin rails to test contact patch stuff (attached to the highest steps)


- Sine and sawtooth waves for bouncing the suspension (behind the origin)


- Sausage kerbs up to 30cm high, angled 0 22.5 and 45 degrees to the direction of the road, to see what happens

- and a drive-through restaurant so you can drive in and out of a parking lot

Added a tube for testing car inversion (it doesn't work. even with CSP tire physics not yet.) and a soccer field for testing car soccer (again... not doin)

Also fixed the slope signs getting deleted by accident in the later 0.4 series

Discovered some of the objects had scale on them which was messing up lighting/culling, fixed that.

Added ceilings from 0 to 1m for testing very short cars.

Accidentally moved the signs at one end of the slopes. Should be a bit easier to tell which slope they go with now (they're all placed on a section of paving that slopes at the same rate as the sign says)