Mostly just trying to make MyPy happy!

Also fixed bug in layer.py where we weren't:
a) Setting the index_name to a default value.
b) Weren't using index_name.

Making pydantic leave me alone and giving the correct index name.

Also made sure it's used properly in layer.py.

list_route_names for checking current route names.

remove for removing route and its associated data..

To tidy up __call__ in RouteLayer.

The test

TestRouteLayer::test_query_with_no_index

was failing because when it ran

assert route_layer("Anything").name is None

There were no Routes defined yet, and this meant that

route = [route for route in self.routes if route.name == top_class][0] was raising an error.

If no routes are defined then we can just defualt to RouteChoice().

Created a random_score_threshold_search method in TestRouteSelection for finding optimum score threshold values across all routes, using a random search algorithm.

Also created a fit method in RouteLayer for running the random_score_threshold_search and for

User inputted value was being overruled by hardcoded list.