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/conf/pcm/dsnoop.conf

@@ -6,11 +6,17 @@ pcm.!dsnoop {
 	@args [ CARD DEV SUBDEV FORMAT RATE ]
 	@args.CARD {
 		type string
-		default 0
+		default {
+			@func refer
+			name defaults.pcm.dsnoop.card
+		}
 	}
 	@args.DEV {
 		type string
-		default 0
+		default {
+			@func refer
+			name defaults.pcm.dsnoop.device
+		}
 	}
 	@args.SUBDEV {
 		type string
@@ -20,14 +26,14 @@ pcm.!dsnoop {
 		type string
 		default {
 			@func refer
-			name defaults.pcm.dmix_format
+			name defaults.pcm.dmix.format
 		}
 	}
 	@args.RATE {
 		type integer
 		default {
 			@func refer
-			name defaults.pcm.dmix_rate
+			name defaults.pcm.dmix.rate
 		}
 	}
 	type dsnoop
@@ -98,4 +104,8 @@ pcm.!dsnoop {
 			default 16
 		}
 	}
+	hint {
+		description "Direct sample snooping device"
+		device $DEV
+	}
 }