Handling of worksheet functions from Excel 2010 and newer

[Winfried Donkers]

Hi Eike,

>Attached to https://bugs.freedesktop.org/show_bug.cgi?id=70798 as
>https://bugs.freedesktop.org/attachment.cgi?id=89539
>Note that T.DIST.2T and T.INV.2T weren't correct, see bug comment.

My typing error (which didn't show as I haven't added these functions yet).

I will work on the unit test to include all functions that are currently present.
Has the xlsx file been pushed to master so that I can submit the test patch?

Winfried