Need more GetDistance() methods

[jievince]

S2Polyline::GetDistance(S2Point)
S2Polyline::GetDistance(S2Polyline)

S2Polygon::GetDistance(S2Polyline)
S2Polygon::GetDistance(S2Polygon)

These methods are missed in S2

[jmr]

Use S2ClosestEdgeQuery. If you search for "distance" in s2polygon.h, you'll find this: https://github.com/google/s2geometry/blob/master/src/s2/s2polygon.h#L797

  // For example, to measure the distance from one S2Polygon to another, you
  // can write:
  //   S2ClosestEdgeQuery query(&polygon1.index());
  //   S2ClosestEdgeQuery::ShapeIndexTarget target(&polygon2.index());
  //   S1ChordAngle distance = query.GetDistance(&target);

[jievince]

Thanks!