Reviewed by Adam Barth.

        Attempt to make new-run-webkit-tests --help more sane
        https://bugs.webkit.org/show_bug.cgi?id=37836

        * Scripts/webkitpy/layout_tests/layout_package/dump_render_tree_thread.py:
         - Add a FIXME about options.singly and options.batch_size being different.
        * Scripts/webkitpy/layout_tests/run_webkit_tests.py:
         - Add support for hidden options.
         - Add option groupings to attempt to simplify --help.
         - Fix a bunch of option helps to start with a capitalized verb.
         - Hide a bunch of options which make no sense to users.
         - Sort options in --help.
        * Scripts/webkitpy/layout_tests/run_webkit_tests_unittest.py:
         - Add tests for option sorting.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@59631 268f45cc-cd09-0410-ab3c-d52691b4dbfc