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

test/Makefile.am

@@ -1,6 +1,6 @@
 check_PROGRAMS=control pcm pcm_min latency seq \
 	       playmidi1 timer rawmidi midiloop \
-	       oldapi queue_timer
+	       oldapi queue_timer namehint
 
 control_LDADD=../src/libasound.la
 pcm_LDADD=../src/libasound.la
@@ -13,6 +13,7 @@ rawmidi_LDADD=../src/libasound.la
 midiloop_LDADD=../src/libasound.la
 oldapi_LDADD=../src/libasound.la
 queue_timer_LDADD=../src/libasound.la
+namehint_LDADD=../src/libasound.la
 code_CFLAGS=-Wall -pipe -g -O2
 
 INCLUDES=-I$(top_srcdir)/include