Header cleanup (#1857)

* remove unused include

* remove unused include

* remove unused include

include/igl/IndexComparison.h

@@ -7,7 +7,6 @@
 // obtain one at http://mozilla.org/MPL/2.0/.
 #ifndef IGL_INDEXCOMPARISON_H
 #define IGL_INDEXCOMPARISON_H
-#include <iostream>
 namespace igl{
   // Comparison struct used by sort
   // http://bytes.com/topic/c/answers/132045-sort-get-index

include/igl/fast_winding_number.cpp

@@ -1,6 +1,5 @@
 #include "fast_winding_number.h"
 #include "octree.h"
-#include "knn.h"
 #include "parallel_for.h"
 #include "PI.h"
 #include <vector>

include/igl/octree.cpp

@@ -1,6 +1,5 @@
 #include "octree.h"
 #include <vector>
-#include <queue>
 
 namespace igl {
   template <typename DerivedP, typename IndexType, typename DerivedCH,