gst/mxf/: Add support for SMPTE D10 essence (SMPTE 386M).

gst/mxf/: Add support for SMPTE D10 essence (SMPTE 386M).

Original commit message from CVS:
* gst/mxf/Makefile.am:
* gst/mxf/mxfd10.c: (mxf_is_d10_essence_track),
(mxf_d10_picture_handle_essence_element),
(mxf_d10_sound_handle_essence_element), (mxf_d10_create_caps):
* gst/mxf/mxfd10.h:
* gst/mxf/mxfdemux.c:
(gst_mxf_demux_handle_header_metadata_update_streams):
Add support for SMPTE D10 essence (SMPTE 386M).
* gst/mxf/mxfparse.c:
(mxf_metadata_generic_picture_essence_descriptor_set_caps):
Don't set width/height and PAR on the caps as those values are
wrong for most files (height is sometimes the height of a field
and aspect ratio is some random value).
* gst/mxf/mxfaes-bwf.c: (mxf_bwf_create_caps),
(mxf_aes3_create_caps):
Fix calculation of block align if it isn't set in the descriptor.