- Part of #1318.
- Part of #1378.
- `RouteHandler` now accepts an additional `XPCServerSession` which
include a disconnect handler.
- `XPCServer` configures a session for each client connection and passes
it to every route handler.
- `XPCServer.route(fn:)` can be used to wrap existing route handlers
that don't care about sessions.
- `XPCClient` adds functions to support client-side session handling.
- Update all existing routes.
J Logan