ext/theora/: Added cropping option to theora decoder.

ext/theora/: Added cropping option to theora decoder.

Original commit message from CVS:
* ext/theora/theoradec.c: (gst_theora_dec_class_init),
(gst_theora_dec_init), (theora_get_formats),
(theora_dec_src_convert), (theora_dec_sink_convert),
(theora_dec_src_query), (theora_dec_src_event), (theora_dec_event),
(theora_dec_chain), (theora_dec_set_property),
(theora_dec_get_property):
* ext/theora/theoraenc.c: (gst_border_mode_get_type),
(gst_theora_enc_class_init), (gst_theora_enc_init),
(theora_enc_sink_link), (theora_enc_chain),
(theora_enc_set_property), (theora_enc_get_property):
Added cropping option to theora decoder.
Added border option to theora encoder.