Clean up low-zoom layer

- Move preserved railways and monorails from low-zoom layer #roads-low-zoom
- Remove funicular rule that never gets hit
Merge branch 'roadsv1.1' of https://github.com/math1985/openstreetmap-carto into math1985-roads
Re-instate funiculars at low zooms.

The original omission in the SQL query is the bug, and it makes sense
to treat them similarly to other railway types, and to have them
appearing not after their stations when zooming in.