(struct sound): Renamed from struct sound_file.

(struct sound): Renamed from struct sound_file.
(struct sound): Add members `data' and `header_size'.
(enum sound_attr): Add SOUND_DATA.
(current_sound, current_sound_device): Variables renamed from
sound_file and sound_device.
(parse_sound): Parse :data.
(parse_sound): Handle sound data in strings.
(find_sound_type): Function renamed from find_sound_file_type.
(wav_init, au_init): Fail if sound's header_size is smaller than
needed header size.
(wav_play, au_play): Play sounds from string data.