fix dragging, snapping, pushing and pass all tests

Author: antoinerg

package-lock.json

@@ -64,11 +64,11 @@
     "convex-hull": "^1.0.3",
     "country-regex": "^1.1.0",
     "d3": "^3.5.12",
+    "d3-sankey": "git://github.com/antoinerg/d3-sankey.git#4f37ed8d3578b545a8569ecd74583f373768e900",
     "d3-array": "1",
     "d3-collection": "1",
     "d3-force": "^1.0.6",
     "d3-interpolate": "1",
-    "d3-sankey": "^0.7.1",
     "delaunay-triangulate": "^1.1.6",
     "es6-promise": "^3.0.2",
     "fast-isnumeric": "^1.1.2",