Add missing t-test function from Data Analysis Toolkit.
This Feature request has been fixed in LO 4.3 by Tomaz Vajngerl see: https://wiki.documentfoundation.org/ReleaseNotes/4.3#Statistics_Wizard_.28alternative_to_Excel.27s_Add-in_.22Analysis_ToolPak.22.29 Perhaps we should close this bug/feature request