add theme function. And provide two themes default.

WinAlfred/Helper/Settings.cs

@@ -0,0 +1,44 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text;
+
+namespace WinAlfred.Helper
+{
+    public class Settings
+    {
+        private string configPath = Directory.GetCurrentDirectory() + "\\config.ini";
+        private static readonly Settings settings = new Settings();
+        IniParser parser = new IniParser("config.ini");
+
+        public string Theme { get; set; }
+
+        private Settings()
+        {
+            LoadSettings();
+        }
+
+        private void LoadSettings()
+        {
+            if (!File.Exists(configPath)) File.Create(configPath);
+            Theme = parser.GetSetting("ui", "theme");
+        }
+
+        public void SaveSettings()
+        {
+            parser.AddSetting("ui", "theme", Theme);
+            parser.SaveSettings();
+        }
+
+        public static Settings Instance
+        {
+            get
+            {
+                return settings;
+            }
+        }
+
+
+    }
+}