ENH: Changed VTK license to BSD

Copyright.txt

@@ -3,7 +3,7 @@
   Program:   Visualization Toolkit
   Module:    Copyright.txt
 
-Copyright (c) 1993-2007 Ken Martin, Will Schroeder, Bill Lorensen 
+Copyright (c) 1993-2008 Ken Martin, Will Schroeder, Bill Lorensen 
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without
@@ -20,9 +20,6 @@ modification, are permitted provided that the following conditions are met:
    of any contributors may be used to endorse or promote products derived
    from this software without specific prior written permission.
 
- * Modified source versions must be plainly marked as such, and must not be
-   misrepresented as being the original software.
-
 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS''
 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE