mp_ring: remove unused function

This was needed for ao_jack.c., but not anymore.
dec_audio: adjust "large" decoding amount

This used to be in bytes, now it's in samples. Divide the value by 8
(assuming a typical audio format, float samples with 2 channels).

Fix some editing mistake or non-sense about the extra buffering added
(1<<x instead of x<<5).

Also sneak in a s/MPlayer/mpv/.
manpage: mark DTS-HD passthough as broken
audio: drop "_NE"/"ne" suffix from audio formats

You get the native format by not appending any suffix to the format.

This change includes user-facing names, e.g. for the --format option.