volume: added mute support

If a channel is muted we return 0. Something like "Muted" would be
nice, but lets not break progressbars. If it doesn't concern you, then
return what ever you want...

thermal.lua

@@ -18,7 +18,7 @@ local function worker(format, thermal_zone)
     -- Get an ACPI thermal zone
     local f = io.open("/proc/acpi/thermal_zone/" .. thermal_zone .. "/temperature")
     -- Fix your ACPI setup, or find another source of temperature
-    -- exposed trough /sys, if a thermal_zone can't be found.
+    -- exposed trough /sys, if a thermal_zone can't be found
     if not f then return {"N/A"} end
     local line = f:read("*line")
     f:close()

volume.lua

@@ -6,7 +6,10 @@
 -- {{{ Grab environment
 local io = { popen = io.popen }
 local setmetatable = setmetatable
-local string = { match = string.match }
+local string = {
+    find = string.find,
+    match = string.match
+}
 -- }}}
 
 
@@ -22,9 +25,10 @@ local function worker(format, channel)
     f:close()
 
     local volume_level = string.match(mixer, "([%d]?[%d]?[%d])%%")
-
-    -- Don't break progressbars
-    if volume_level == nil then return {0} end
+    -- If muted return 0 (not "Mute") so we dont break progressbars
+    if string.find(mixer, "%[off%]") or volume_level == nil then
+        volume_level = 0
+    end
 
     return {volume_level}
 end