Library update. GTK GUI is almost ready to ship.

* Not an XLS.xls: For testing an invalid file with an xls extension.

* MainWindow.cs: Implement library changes.

* PartitionWorkflow.fs: Added delegate for when entry is added, but
  overallocates. Not information was passed previously.
Added overloaded method for WritetoXLS() so a directory chooser is
  invoked if everything checks out. This was mainly for GTK UI as
  previously a user would choose a directory, but then get an error if
  there partitions weren't correct.


* Debug NPOI.fsx: Updated to use Release binaries

* Debug Workflows.fsx: *pdated to use Release binaries and Library
  changes.

* VPPList-Buddy.fsproj: