First round of dead file removal

experimental/visual_studio_plugin/src/MsAd7.BaseImpl/ExtensionMethods.cs

-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using Microsoft.VisualStudio.Debugger.Interop;
-
-namespace Google.MsAd7.BaseImpl
-{
-  public static class ExtensionMethods
-  {
-    public static bool HasFlag(this enum_THREADPROPERTY_FIELDS a, enum_THREADPROPERTY_FIELDS b) {
-      return ((uint) a & (uint) b) != 0;
-    }
-
-    public static bool HasFlag(this enum_DEBUGPROP_INFO_FLAGS a, enum_DEBUGPROP_INFO_FLAGS b)
-    {
-      return ((uint)a & (uint)b) != 0;
-    }
-
-    public static bool Equals(this TEXT_POSITION a, TEXT_POSITION b) {
-      return (a.dwLine == b.dwLine) && (a.dwColumn == b.dwColumn);
-    }
-  }
-}