void remove() {
      if (!removed) {
        from.removeEdge(this);
        to.removeEdge(reversed);
        removed = true;
      }
    }
Processes the added geometries and returns the merged linestrings.
<p>
Can be called more than once.
planetiler-core/src/main/java/com/onthegomap/planetiler/util/LoopLineMerger.java