[Lucene.Net] SpellChecker Bug

[Björn Kremer]

Hello,

there is a little bug in the SpellChecker.cs class. The finalizer of 
this class calls the close method even if the SpellChecker is already 
closed. This causes an unhandled exception.

This should work better:
    ~SpellChecker()
      {
         if (closed == false)
         {
            this.Close();
         }
      }

Thank You
Björn