gst/wavparse/gstwavparse.*: Add push (streaming) mode to wavparse (fixes #337625)

gst/wavparse/gstwavparse.*: Add push (streaming) mode to wavparse (fixes #337625)

Original commit message from CVS:
* gst/wavparse/gstwavparse.c: (gst_wavparse_base_init),
(gst_wavparse_class_init), (gst_wavparse_dispose),
(gst_wavparse_reset), (gst_wavparse_init),
(gst_wavparse_create_sourcepad), (gst_wavparse_parse_adtl),
(gst_wavparse_parse_cues), (gst_wavparse_parse_file_header),
(gst_wavparse_stream_init), (gst_wavparse_perform_seek),
(gst_wavparse_peek_chunk_info), (gst_wavparse_peek_chunk),
(gst_wavparse_stream_headers), (gst_wavparse_parse_stream_init),
(gst_wavparse_send_event), (gst_wavparse_add_src_pad),
(gst_wavparse_stream_data), (gst_wavparse_loop),
(gst_wavparse_chain), (gst_wavparse_srcpad_event),
(gst_wavparse_sink_activate), (gst_wavparse_sink_activate_pull),
(gst_wavparse_change_state), (plugin_init):
* gst/wavparse/gstwavparse.h:
Add push (streaming) mode to wavparse (fixes #337625)