volume: move volume functions into a lib

Also add some notification when changing the volume. Also move
sharetags to the `lib/` directory. And modify `loadrc` to be able to
load modules.

lib/volume.lua

@@ -0,0 +1,52 @@
+-- Handle volume (through pulseaudio)
+
+local awful        = require("awful")
+local naughty      = require("naughty")
+local tonumber     = tonumber
+local string       = string
+local os           = os
+local setmetatable = setmetatable
+
+module("volume")
+
+local volid = nil
+local function change(what)
+   os.execute("amixer -q sset Master " .. what, false)
+   -- Read the current value
+   local out = awful.util.pread("amixer sget Master")
+   local vol, mute = out:match("([%d]+)%%.*%[([%l]*)")
+   if not mute or not vol then return end
+
+   vol = tonumber(vol)
+   local icon = "high"
+   if mute ~= "on" or vol == 0 then
+      icon = "muted"
+   elseif vol < 30 then
+      icon = "low"
+   elseif vol < 60 then
+      icon = "medium"
+   end
+   icon = "/usr/share/icons/gnome/32x32/status/audio-volume-" .. icon .. ".png"
+
+   volid = naughty.notify({ text = string.format("%3d %%", vol),
+			    icon = icon,
+			    font = "Free Sans Bold 24",
+			    replaces_id = volid }).id
+end
+
+function increase()
+   change("5%+")
+end
+
+function decrease()
+   change("5%-")
+end
+
+function toggle()
+   change("toggle")
+end
+
+-- run pavucontrol
+function mixer()
+   awful.util.spawn("pavucontrol", false)
+end