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/cards/ATIIXP-MODEM.conf

@@ -19,4 +19,5 @@ ATIIXP-MODEM.pcm.modem.0 {
 	slave.format S16_LE
 	ttable.0.1 1
 	ttable.1.0 0
+	hint 0
 }

src/conf/cards/HDA-Intel.conf

@@ -19,6 +19,10 @@ HDA-Intel.pcm.front.0 {
 		name "PCM Playback Volume"
 		card $CARD
 	}
+	hint {
+		description "Front speakers and multichannel output"
+		device 0
+	}
 }	
 
 # default with dmix+softvol & dsnoop
@@ -49,6 +53,17 @@ HDA-Intel.pcm.default {
 			strings [ "dsnoop:" $CARD ]
 		}
 	}
+	hint {
+		description "Default dmix+softvol + dsnoop device"
+		device_output {
+			@func refer
+			name defaults.pcm.dmix.device
+		}
+		device_input {
+			@func refer
+			name defaults.pcm.dsnoop.device
+		}
+	}
 }
 
 <confdir:pcm/surround40.conf>
@@ -125,6 +140,10 @@ HDA-Intel.pcm.iec958.0 {
 			]
 		}
 	}
+	hint {
+		description "IEC958 (S/PDIF) Output"
+		device 1
+	}
 }
 
 <confdir:pcm/modem.conf>
@@ -137,4 +156,5 @@ HDA-Intel.pcm.modem.0 {
 	type hw
 	card $CARD
 	device 6
+	hint 0
 }

src/conf/cards/ICH-MODEM.conf

@@ -12,4 +12,5 @@ ICH-MODEM.pcm.modem.0 {
 	type hw
 	card $CARD
 	device 0
+	hint 0
 }