scopes: don't use shared context

OpenGL shared contexts (through Qt at least) seem to be buggy. Scopes have been
shifted to a non-shared approach as a result.

app/main.cpp

@@ -50,9 +50,6 @@ int main(int argc, char *argv[]) {
   format.setProfile(QSurfaceFormat::CoreProfile);
   QSurfaceFormat::setDefaultFormat(format);
 
-  // Try to share OpenGL contexts
-  QApplication::setAttribute(Qt::AA_ShareOpenGLContexts);
-
   // Create application instance
   QApplication a(argc, argv);