add snd_device_name_hint() function and initial implementation

- add snd_device_name_hint() and snd_device_name_free_hint() functions
- add snd_ctl_iface_conf_name() functions
- do not accept parameters for the plugin definition without @args section
- add defaults.pcm.dmix.card/device and dsnoop.card/device definitions
- add hints for HDA-Intel.conf, pcm/dmix.conf, pcm/dsnoop.conf and alsa.conf
- add test/namehint test utility
- doxygen related cleanups

src/mixer/simple_none.c

@@ -982,10 +982,14 @@ static int get_volume_ops(snd_mixer_elem_t *elem, int dir,
 static int init_db_range(snd_hctl_elem_t *ctl, struct selem_str *rec);
 
 /* convert to index of integer array */
+#ifndef DOC_HIDDEN
 #define int_index(size)	(((size) + sizeof(int) - 1) / sizeof(int))
+#endif
 
 /* max size of a TLV entry for dB information (including compound one) */
+#ifndef DOC_HIDDEN
 #define MAX_TLV_RANGE_SIZE	256
+#endif
 
 /* parse TLV stream and retrieve dB information
  * return 0 if successly found and stored to rec,