examples/seeking/: Added app for playback speed testing.

examples/seeking/: Added app for playback speed testing.

Original commit message from CVS:
* examples/seeking/Makefile.am:
* examples/seeking/scrubby.c: (gst_element_factory_make_or_warn),
(dynamic_link), (setup_dynamic_link), (make_wav_pipeline),
(make_playerbin_pipeline), (format_value), (update_scale),
(speed_cb), (seek_cb), (do_seek), (start_seek), (stop_seek),
(play_cb), (pause_cb), (stop_cb), (print_message), (bus_message),
(print_usage), (main):
Added app for playback speed testing.

* examples/seeking/seek.c: (dynamic_link),
(make_avi_msmpeg4v3_mp3_pipeline), (make_avi_pipeline),
(make_mpeg_pipeline), (do_seek), (set_update_scale),
(message_received), (main):
Updated seek example.