v0.7.40

• Import non-standard top-level GeoJSON metadata, so it can be re-exported by adding the -o metadata flag. This includes top-level crs, id and any other properties that are not part of the GeoJSON spec.
• Improved smoothness of medial lines (used in topological and fill-gaps buffer modes).
• Improved quality of -buffer fill-gaps output.
• Added -buffer fill-gaps merge-islands option.