corrected GL includes

#ifndef OPENGLCANVAS_H

#define OPENGLCANVAS_H

#ifndef GL_VERSION_3_1

// GLew might not be needed if a recent version of OpenGL is present

#include <GL/glew.h>

#if (!defined GLEW_VERSION_1_5) || (!defined GL_VERSION_3_1)

        #error OpenGL 3.1 or GLEW 1.5.2 is required

    #error GLEW 1.5.2 is required

#endif

#endif

#include <QGLWidget>

#include <fcntl.h>

#include <unistd.h>

#include "chronos.h"

#include <QTimer>

extern "C" {

#include <ppm.h>

#include <pm.h>

#include <pam.h>

}

#define GL_GLEXT_PROTOTYPES 1

#ifdef __APPLE__

  #include <GL/glext.h>

#endif

#include <QGLWidget>

#include <QTimer>

#include <QFile>

#include <QFileDialog>

#include <fcntl.h>

#include <unistd.h>

#include "chronos.h"

extern "C" {

#include <ppm.h>

#include <pm.h>

#include <pam.h>

}

class OpenGLCanvas : public QGLWidget

{