adjust near clipping plane to give better depth buffer usage

modes/Tunnel.cc

@@ -139,7 +139,7 @@ bool Tunnel::configure (GnomeScreensaver & gs)
     glMatrixMode(GL_PROJECTION);
     glLoadIdentity();
     gluPerspective(60.0, gs.getAspectRatio() / gs.getNumMonitors(),
-            0.01, 1000.0);
+            1.0, 1000.0);
 
     glMatrixMode(GL_MODELVIEW);
     glLoadIdentity();