compiles on linux again

Former-commit-id: 23558d07dac668f708a78b23c1ba188a5bc3d76a

include/igl/ReAntTweakBar.cpp

@@ -3,6 +3,7 @@
 #include <cstdio>
 #include <cstring>
 #include <sstream>
+#include <iostream>
 #include <iomanip>
 #include <map>
 
@@ -212,7 +213,10 @@ int igl::ReTwBar::TwRefreshBar()
 
 int igl::ReTwBar::TwTerminate()
 {
-  return ::TwTerminate();
+  std::cout<<"TwTerminate"<<std::endl;
+  int r = ::TwTerminate();
+  std::cout<<"  "<<r<<std::endl;
+  return r;
 }
 
 bool igl::ReTwBar::save(const char *file_name)

include/igl/draw_beach_ball.cpp

@@ -1,6 +1,15 @@
 #include "draw_beach_ball.h"
 
-#include <OpenGL/GL.h>
+#ifdef __APPLE__
+#  include <OpenGL/gl.h>
+#elif defined(_WIN32)
+#  define NOMINMAX
+#  include <Windows.h>
+#  undef NOMINMAX
+#  include <GL/gl.h>
+#else
+#  include <GL/gl.h>
+#endif
 
 #include <vector>
 #include <cmath>

include/igl/readTGF.cpp

@@ -1,6 +1,6 @@
 #include "readTGF.h"
 
-#include <igl/list_to_matrix.h>
+#include <cstdio>
 
 IGL_INLINE bool igl::readTGF(
   const std::string tgf_filename,
@@ -130,6 +130,8 @@ IGL_INLINE bool igl::readTGF(
 }
 
 #ifndef IGL_NO_EIGEN
+#include <igl/list_to_matrix.h>
+
 IGL_INLINE bool igl::readTGF(
   const std::string tgf_filename,
   Eigen::MatrixXd & C,