message: Add missing impl to EdgeIndex
diff: @@ -158,6 +158,10 @@ impl<Ix: IndexType> EdgeIndex<Ix>
  }
  }
  +impl<Ix: IndexType> From<Ix> for EdgeIndex<Ix> {
  + fn from(ix: Ix) -> Self { EdgeIndex(ix) }
  +}
  +
  impl<Ix: fmt::Debug> fmt::Debug for EdgeIndex<Ix>
  {
  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
  