gst/subparse/: Add support for SAMI subtitles (#169936).

gst/subparse/: Add support for SAMI subtitles (#169936).

Original commit message from CVS:
Patch by: Young-Ho Cha  <ganadist at chollian net>
* gst/subparse/Makefile.am:
* gst/subparse/gstsubparse.c: (gst_sub_parse_dispose),
(parser_state_dispose), (gst_sub_parse_data_format_autodetect),
(gst_sub_parse_format_autodetect), (feed_textbuf),
(gst_subparse_type_find), (plugin_init):
* gst/subparse/gstsubparse.h:
* gst/subparse/samiparse.c:
* gst/subparse/samiparse.h:
Add support for SAMI subtitles (#169936).