Add a linear feature layer

Is it possible to add linear features in geojson format? Similar functionality as markers, but linear features rather than point features.

Thanks for your consideration.

The issue does not name any files or tests. Start by tracing the existing marker support and how GeoJSON reaches the Google Maps rendering layer; clarify the expected line-feature inputs and API before coding. Done means linear GeoJSON features render on maps with behavior comparable to markers, with coverage for the supported input.

Written by the indexing model from the issue text.