Rename inconsistently named parameters in the configuration

Both app.config parameters `maximum_snapping_radius`(routing) and `maximum_search_radius`(matrix) serve the purpose to define the maximum distance from the graph a given coordinate may have in order to find a nearest point on the graph. Serving the same purpose, they should have the same name. `maximum_snapping_radius` is to be preferred as it states more clearly what the parameter is about.