Improve plot comparison scripts. * compare_plot_demos.m: pass toolkits{} to html_compare_plot_demos. Give instructions for toolkit matlab. Fix whitespace issue. * dump_demos.m: fix typo in default dir. Consistently use dump_plot_demos.m for main worker script. Create diary and error messages for inclusion in html page. Set random seed for better comparison. * html_plot_demos_template.html: Allow variable toolkits (removed hard-coded gnuplot, matlab, fltk sequence). Fix some whitespace issues. * html_compare_plot_demos.m: Rewrite docstring. The instructions are no longer needed because compare_plot_demos handles them. Add "toolkits" and column_width param. Dynamically add toolkits in html, add diary.log link.

%!function r = f1 ()
%!  ls = svd (1);
%!  r = eval ("ls -1;");
%!endfunction
%!function r = f2 ()
%!  [u,ls,v] = svd (1);
%!  r = eval ("ls -1;");
%!endfunction
%!function r = f3 (ls)
%!  r = eval ("ls -1;");
%!endfunction

%!test
%! ## Windows systems can't run "ls -1"
%! if (! ispc ())
%!   assert (f1 (), 0);
%!   assert (f2 (), 0);
%!   assert (ischar (f3 ()), true);
%!   assert (f3 (1), 0);
%! endif