Use OpenGL line smoothing when multisample is not available. * gl-render.cc (opengl_renderer::init_gl_context): Check whether multisample is enabled and use GL_LINE_SMOOTH if it is not. * gl-render.cc (opengl_renderer::setup_opengl_transformation). Remove call to disable GL_LINE_SMOOTH. * gl-render.cc (opengl_renderer::draw_axes_children): Remove call to enable GL_LINE_SMOOTH. * gl-render.cc (opengl_renderer::draw_axes): Disable GL_LINE_SMOOTH for axes lines, but re-enable for axes children.

Copyright notices are intentionally omitted from the files in the
examples directory.  We don't want copyright notices cluttering the
manual.