New spreadsheet functions

[Regina Henschel]

Hi all,

it might be overlooked, so I want to draw your attention to the commit 
of CWS calcishmakkica in r1381446 to r1381452 on 5.Sept. 2012. (You 
remember the long lasting attempt to get it?) It contains in the main 
the work of Marina Plakalovic from the OpenOffice.org Summer 2010 
Internship. She has implemented the function XOR, COUNTIFS, AVERAGEIFS, 
and SUMIFS. Daniel Rentz added Excel filters. Thanks to Eike, who 
rebased the CWS and has brought this all forward, and to Andrew, who 
finally committed it.

There are still things to do. There are no help texts and the reference 
in the Wiki [1] is missing too.

Kind regards
Regina

[1] Start for example in 
http://wiki.openoffice.org/wiki/Documentation/How_Tos/Calc:_Functions_listed_alphabetically