Use robust crate for orientation tests

[urschrei]

See previous discussion: #380,

We'll need to resolve the following issues around num and compatibility first: georust/robust#3, georust/robust#5

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Update: this issue now tracks the progress in converting the algo. traits to use the robust predicates.

• Kernel abstraction (Robust Winding Order #502)
• Orient and WindingOrder (Robust Winding Order #502)
• ConvexHull (Robustify convex hull impl #504)
• ExtremePoints (Robust ExtremePoint trait #505)
• Contains (Robust Intersect and Contains #511)
• Intersects (Robust Intersect and Contains #511)

[frewsxcv]

Was this completed in #502? cc @rmanoka

[urschrei]

I think we've got some instances left to track down, but need to have a careful look.

[rmanoka]

Yeah, we use it now for Winding and Orient traits. Contains , Intersects are the prominent ones that need to use it yet.

[rmanoka]

Converting this issue into a tracker for making the existing traits use robust preds.