docs/design/part-gstghostpad.txt: Update ascii art in documentation.

docs/design/part-gstghostpad.txt: Update ascii art in documentation.

Original commit message from CVS:
* docs/design/part-gstghostpad.txt:
Update ascii art in documentation.
* gst/gstghostpad.c: (gst_proxy_pad_do_internal_link),
(gst_proxy_pad_set_target_unlocked), (gst_proxy_pad_init),
(gst_ghost_pad_parent_set), (gst_ghost_pad_parent_unset),
(gst_ghost_pad_internal_do_activate_push),
(gst_ghost_pad_internal_do_activate_pull),
(gst_ghost_pad_do_activate_push), (gst_ghost_pad_do_activate_pull),
(gst_ghost_pad_do_link), (gst_ghost_pad_do_unlink),
(gst_ghost_pad_dispose), (gst_ghost_pad_new_full),
(gst_ghost_pad_set_target):
Small cleanups and leak fixes.
Remove some checks now that the internal pad is never NULL.
Fix the case where linking pads without a target would create nasty
criticals. Fixes #341029.
Don't assign a GstPadLinkReturn to a gboolean and mess up the return
value of _set_target().
* tests/check/gst/gstghostpad.c: (GST_START_TEST),
(gst_ghost_pad_suite):
Some more tests for creating and linking untargeted ghostpads.