We use topojson.borders() (a proposed extension of topojson.mesh()) to extract borders arcs; then we manipulate the borders childishly (outrageously? — it makes some countries vanish!) by keeping only the first and last point of each arc.
Research by Philippe Rivière for topojson issue #17.
forked from mbostock‘s block: World Map
forked from Fil‘s block: topojson borders