Dont allow drawing incorrect polygons

[rafaqz]

When we draw polygons movement of points should stop at the point where a line would intersect another to create an incorrect polygon. We can probably use tools from GeometryOps.jl to do this once it has stabilized.

[asinghvi17]

would need self-intersection utils which are present in GeometryBasics.

[rafaqz]

Ah ok that should be enough then.