Use utf symbols for some bat states. Mention LuaFileSystem in mdir.lua

bat.lua

@@ -23,9 +23,9 @@ module("vicious.bat")
 function worker(format, batid)
     -- Initialise tables
     local battery_state = {
-        ["full"]        = "*",
+        ["full"] = "↯",
-        ["unknown"]     = " ",
+        ["unknown"] = "⌁",
-        ["charged"]     = "*",
+        ["charged"] = "↯",
         ["charging"] = "+",
         ["discharging"] = "-"
     }

batat.lua

@@ -18,9 +18,9 @@ function worker(format)
     -- Initialise tables
     local battery_info  = {}
     local battery_state = {
-        ["full"]        = "*",
+        ["full"] = "↯",
-        ["unknown"]     = " ",
+        ["unknown"] = "⌁",
-        ["charged"]     = "*",
+        ["charged"] = "↯",
         ["charging"] = "+",
         ["discharging"] = "-"
     }

mdir.lua

@@ -15,8 +15,11 @@ module("vicious.mdir")
 
 -- {{{ Maildir widget type
 function worker(format, mdir)
-    -- Widgets like this one are not agressive like CPU or NET, so we
+    -- Like with the mbox count widget, we would benefit from the
-    -- can keep it simple, find is OK with me if we execute every >60s
+    -- LuaFileSystem library. However, we didn't rely on extra
+    -- libraries to this point so we won't start now. Widgets like
+    -- this one are not agressive like CPU or NET, so we can keep it
+    -- simple, find is OK with me if we execute every >60s
     --
     -- Initialise counters
     local newcount = 0