alsa: rework mixer logic

Completely rework mixer logic. This now allows controlling a full set of
elements from a single sink's volume slider/mute button.

This also introduces sink and source "ports" that can be used to choose
different input or output ports with the UI. (i.e. "mic"/"line-in" or
"speaker"/"headphones".

The mixer paths and device maps are now configered in external
configuration files and can be tweaked as necessary.

src/modules/alsa/mixer/paths/analog-input.conf.common

@@ -0,0 +1,239 @@
+# Mixer path for PulseAudio's ALSA backend. If multiple options by the
+# same id are discovered they will be suffixed with a number to
+# distuingish them, in the same order they appear here.
+#
+# Source selection should use the following names:
+#
+#       input                       -- If we don't know the exact kind of input
+#       input-microphone
+#       input-microphone-internal
+#       input-microphone-external
+#       input-linein
+#       input-video
+#       input-radio
+#       input-docking-microphone
+#       input-docking-linein
+#       input-docking
+#
+#  We explicitly don't want to wrap the following sources:
+#
+#       CD
+#       Synth/MIDI
+#       Phone
+#       Mix
+#       Digital/SPDIF
+#       Master
+#       PC Speaker
+#
+
+;;; 'Input Source Select'
+
+[Element Input Source Select]
+enumeration = select
+
+[Option Input Source Select:Input1]
+name = input
+priority = 10
+
+[Option Input Source Select:Input2]
+name = input
+priority = 5
+
+;;; 'Input Source'
+
+[Element Input Source]
+enumeration = select
+
+[Option Input Source:Mic]
+name = input-microphone
+priority = 20
+
+[Option Input Source:Microphone]
+name = input-microphone
+priority = 20
+
+[Option Input Source:Front Mic]
+name = input-microphone
+priority = 19
+
+[Option Input Source:Front Microphone]
+name = input-microphone
+priority = 19
+
+[Option Input Source:Line]
+name = input-linein
+priority = 18
+
+[Option Input Source:Line-In]
+name = input-linein
+priority = 18
+
+[Option Input Source:Line In]
+name = input-linein
+priority = 18
+
+;;; ' Capture Source'
+
+[Element Capture Source]
+enumeration = select
+
+[Option Capture Source:TV Tuner]
+name = input-video
+
+[Option Capture Source:FM]
+name = input-radio
+
+[Option Capture Source:Mic/Line]
+name = input
+
+[Option Capture Source:Line/Mic]
+name = input
+
+[Option Capture Source:Mic]
+name = input-microphone
+
+[Option Capture Source:Microphone]
+name = input-microphone
+
+[Option Capture Source:Int Mic]
+name = input-microphone-internal
+
+[Option Capture Source:Int DMic]
+name = input-microphone-internal
+
+[Option Capture Source:Internal Mic]
+name = input-microphone-internal
+
+[Option Capture Source:iMic]
+name = input-microphone-internal
+
+[Option Capture Source:i-Mic]
+name = input-microphone-internal
+
+[Option Capture Source:Internal Microphone]
+name = input-microphone-internal
+
+[Option Capture Source:Front Mic]
+name = input-microphone
+
+[Option Capture Source:Front Microphone]
+name = input-microphone
+
+[Option Capture Source:Rear Mic]
+name = input-microphone
+
+[Option Capture Source:Mic1]
+name = input-microphone
+
+[Option Capture Source:Mic2]
+name = input-microphone
+
+[Option Capture Source:D-Mic]
+name = input-microphone
+
+[Option Capture Source:IntMic]
+name = input-microphone-internal
+
+[Option Capture Source:ExtMic]
+name = input-microphone-external
+
+[Option Capture Source:Ext Mic]
+name = input-microphone-external
+
+[Option Capture Source:E-Mic]
+name = input-microphone-external
+
+[Option Capture Source:e-Mic]
+name = input-microphone-external
+
+[Option Capture Source:LineIn]
+name = input-linein
+
+[Option Capture Source:Analog]
+name = input
+
+[Option Capture Source:Line]
+name = input-linein
+
+[Option Capture Source:Line-In]
+name = input-linein
+
+[Option Capture Source:Line In]
+name = input-linein
+
+[Option Capture Source:Video]
+name = input-video
+
+[Option Capture Source:Aux]
+name = input
+
+[Option Capture Source:Aux0]
+name = input
+
+[Option Capture Source:Aux1]
+name = input
+
+[Option Capture Source:Aux2]
+name = input
+
+[Option Capture Source:Aux3]
+name = input
+
+[Option Capture Source:AUX IN]
+name = input
+
+[Option Capture Source:Aux In]
+name = input
+
+[Option Capture Source:AOUT]
+name = input
+
+[Option Capture Source:AUX]
+name = input
+
+[Option Capture Source:Cam Mic]
+name = input-microphone
+
+[Option Capture Source:Digital Mic]
+name = input-microphone
+
+[Option Capture Source:Digital Mic 1]
+name = input-microphone
+
+[Option Capture Source:Digital Mic 2]
+name = input-microphone
+
+[Option Capture Source:Analog Inputs]
+name = input
+
+[Option Capture Source:Unknown1]
+name = input
+
+[Option Capture Source:Unknown2]
+name = input
+
+[Option Capture Source:Docking-Station]
+name = input-docking
+
+[Option Capture Source:Dock Mic]
+name = input-docking-microphone
+
+;;; Various Boosts
+
+[Element Capture Boost]
+switch = select
+
+[Option Capture Boost:on]
+name = input-boost-on
+
+[Option Capture Boost:off]
+name = input-boost-off
+
+[Element Auto Gain Control]
+switch = select
+
+[Option Auto Gain Control:on]
+name = input-agc-on
+
+[Option Auto Gain Control:off]
+name = input-agc-off