message: Remove reenabling of OpenGL debug callback.
diff: #include <fstream>
  #include <sstream>
  -void GLAPIENTRY
  -MessageCallback( GLenum source,
  - GLenum type,
  - GLuint id,
  - GLenum severity,
  - GLsizei length,
  - const GLchar* message,
  - const void* userParam )
  -{
  - if (severity < GL_DEBUG_SEVERITY_HIGH) {
  - return;
  - }
  -
  - fprintf( stderr, "GL CALLBACK: %s type = 0x%x, severity = 0x%x, message = %s\n",
  - ( type == GL_DEBUG_TYPE_ERROR ? "** GL ERROR **" : "" ),
  - type, severity, message );
  -}
  -
  namespace NovelRT {
  bool NovelRenderingService::initializeRenderPipeline(const int displayNumber) {
  @@ -75,9 +57,6 @@ bool NovelRenderingService::initializeRenderPipeline(const int displayNumber) {
  std::cerr << "ERROR: Failed to initialise glad." << std::endl;
  return -1;
  }
  - // During init, enable debug output
  - glEnable ( GL_DEBUG_OUTPUT );
  - glDebugMessageCallback( MessageCallback, 0 );
  std::cout << "GL_VERSION : " << glGetString(GL_VERSION) << std::endl;
  std::cout << "GL_SHADING_LANGUAGE_VERSION: " << glGetString(GL_SHADING_LANGUAGE_VERSION) << std::endl;
  