Switched the parenting collection back to derive directly from the .NET Framework collection class to simplify the implementation of the DisposeItems() method; fixed some documentation errors in one of the rectangle packers

git-svn-id: file:///srv/devel/repo-conversion/nusu@41 d2e56fa2-650e-0410-a79f-9358c0239efd

Source/Tracking/ProgressionTracker.cs

@@ -17,6 +17,7 @@ You should have received a copy of the IBM Common Public
 License along with this library
 */
 #endregion
+
 using System;
 using System.Collections.Generic;
 using System.Threading;