Original commit message from CVS:
Patch by: Kamil Pawlowski  <kamilpe gmail com>
* gst/subparse/Makefile.am:
* gst/subparse/gstsubparse.c:
(gst_sub_parse_data_format_autodetect),
(gst_sub_parse_format_autodetect), (gst_sub_parse_sink_event),
(gst_subparse_type_find):
* gst/subparse/gstsubparse.h:
* gst/subparse/mpl2parse.c: (mpl2_parse_line), (parse_mpl2):
* gst/subparse/mpl2parse.h:
Add support for MPL2 subtitle format (#413799).