Geometry_Engine: IJoin to take IEnumerable<ICurve> rather than List<ICurve>

[JosefTaylor]

Description:

Currently if you have something like a FreeFormProfile profile, and want all the continuous edges, you must do:

List<PolyCurve> crvs = BH.Engine.Geometry.Compute.IJoin(profile.Edges.ToList());

it would be nice to avoid that ToList(); not just for readability, but also so that this is method is easier for intellisense to find.