Concave hull option for project bounds

[philipbaileynar]

I think we are using convex hulls as an option for the Riverscapes project bounds. They look a little clunky/abstract in the data exchange. What would it take to get to convex hulls? I know convex hulls require more parameterization (point spacing tolerance etc) , but I think we could estimate these crudely using basic project properties (project area, circumference etc).