v0.2.49..v0.2.50 changeset IdSwap.h

diff --git a/hoot-core/src/main/cpp/hoot/core/conflate/IdSwap.h b/hoot-core/src/main/cpp/hoot/core/conflate/IdSwap.h
index e475817..af3d3e4 100644
--- a/hoot-core/src/main/cpp/hoot/core/conflate/IdSwap.h
+++ b/hoot-core/src/main/cpp/hoot/core/conflate/IdSwap.h
@@ -47,6 +47,7 @@ public:
   typedef typename container::const_iterator const_iterator;
 
   IdSwap();
+  IdSwap(ElementId id_1, ElementId id_2) { add(id_1, id_2); }
 
   /**
    * @brief add