ext/theora/: Added a theora encoder, grouped the encoder and decoder into the same...

ext/theora/: Added a theora encoder, grouped the encoder and decoder into the same plugin.

Original commit message from CVS:
* ext/theora/Makefile.am:
* ext/theora/theora.c: (plugin_init):
* ext/theora/theoradec.c: (theora_dec_change_state):
* ext/theora/theoraenc.c: (gst_theora_enc_base_init),
(gst_theora_enc_class_init), (gst_theora_enc_init),
(theora_enc_sink_link), (theora_enc_event), (theora_push_packet),
(theora_enc_chain), (theora_enc_change_state),
(theora_enc_set_property), (theora_enc_get_property):
Added a theora encoder, grouped the encoder and decoder into the
same plugin.