ext/amrnb/: Further fancyfication.

ext/amrnb/: Further fancyfication.

Original commit message from CVS:
* ext/amrnb/amrnbdec.c: (gst_amrnbdec_init),
(gst_amrnbdec_setcaps), (gst_amrnbdec_chain),
(gst_amrnbdec_state_change):
* ext/amrnb/amrnbenc.c: (gst_amrnbenc_init),
(gst_amrnbenc_setcaps), (gst_amrnbenc_chain),
(gst_amrnbenc_state_change):
* ext/amrnb/amrnbenc.h:
* ext/amrnb/amrnbparse.c: (gst_amrnbparse_init),
(gst_amrnbparse_query):
Further fancyfication.
Use _take to get writable data from the adapter.
Precalc packet duration.
Handle disconts.
Forward _push to upstream.
Post error messages when something goes wrong.
Remove old code in amrnbparse.
Don't ignore query results from upstream.