CompoundRouteRule is unusable in a schematic

Passing a single style to `route!(g, ...)` with a CompoundRouteRule doesn't correctly end up giving routing methods a vector of styles, and passing a vector of styles doesn't call a valid RouteComponent constructor. The documentation is also not very detailed and doesn't specify the use of `waydirs` or the optional use of a style vector.

Start by locating the `route!(g, ...)` entry point and the `CompoundRouteRule` and `RouteComponent` definitions. Trace how scalar and vector styles are passed to routing methods, then review the documentation around `waydirs` and style vectors. Done means both style forms construct valid routing components and the supported options are documented.

Written by the indexing model from the issue text.