Access2Base - PATCH-01 Field.setValue

setValue gives erroneously an error message when argument is Null and field is nullable
https://forum.openoffice.org/en/forum/viewtopic.php?f=47&t=61447&sid=48e231a12084933d9da1b47e50b186ea#p323714

Change-Id: Ic96e50f4c752f5fa38e8f40e80692f166fd88e4a