DStability - Shapely accuracy leads to invalid new layers

[breinbaas]

In the current version of geolib adding new layers to a DStability geometry can lead to errors in the geometry. This seems to be related to the accuracy of the coordinates. Here is an example of a layer that has been added programmatically;

As you can see the rightmost point of the new layer is not connected to the geometry which leads to an error if you want to calculate this using DStability.

[breinbaas]

The solution is easy and implemented in #171

Since it was a very small code change I have added it to the other PR but if you want to keep this seperate the code to be changed is;

def connect_layers(self, layer1: PersistableLayer, layer2: PersistableLayer):
        """Connects two polygons by adding a the missing points on the polygon edges. Returns the two new polygons."""
        linestring1 = self.to_shapely_linestring(layer1.Points)
        linestring2 = self.to_shapely_linestring(layer2.Points)

        # Create a union of the two polygons and polygonize it creating two connected polygons
        union = linestring1.union(linestring2, grid_size=1e-3) # ADDED GRIDSIZE PARAMETER
        result = [geom for geom in polygonize(union)]

        # If the result has two polygons, we return them, otherwise we return the original polygons
        if len(result) == 2:
            return result[0].exterior, result[1].exterior
        else:
            return linestring1, linestring2

Now everything looks fine;