One special dictionary

由于项目一个功能需要，可以将关键字的值叠加加来，最终可以获取对这些关键字都做了些什么操作。

Generic Programming is very powerful.

      /// <summary>
      ///
      /// </summary>
      /// <typeparam name="TKey"></typeparam>
      public class CXSpecialDictionary<TKey> : Dictionary<TKey, string>
      {
          /// <summary>
          ///
          /// </summary>
         /// <param name="key"></param>
         /// <returns></returns>
         public new string this[TKey key]
         {
             get { if (base.ContainsKey(key)) return base[key]; return ""; }
             set { if (base.ContainsKey(key)) base[key] = base[key] + "\r\n" + value; else base.Add(key, value); }
         }
         /// <summary>
         ///
         /// </summary>
         /// <param name="key"></param>
         /// <param name="value"></param>
         public new void Add(TKey key, string value)
         {
             if (base.ContainsKey(key))
             {
                 base[key] = base[key] + "\r\n" + value;
                 return;
             }
             base.Add(key, value);
         }

     }