o RooRealSumPdf

     - In expectedEvents() add check for negative return value
       and issue a logEvalError() which will trigger MinuitGlue
       intervention to deal with this

   o RooNLLVar

     - Pass observed event count as Double_t to extended term


   o RooAbsPdf

     - Make extendedTerm take Nobserved as double instead of int to
       accomodate use of asimov datasets


   o RooMinuit

     - Add member setMaxEvalMultiplies() to control the max number
       of NLL evaluations pass to minuit. The default remains
       500 (and is always multiplied by nPar)


   o RooWorkspace

     - Add extra check in autoImportClassCode() that checks
       if a class exists in a ROOT shared library and skips
       those for import. This prevents the attempted import
       of ROOT-native classes into a workspace in binary
       ROOT distributions


git-svn-id: http://root.cern.ch/svn/root/branches/v5-30-00-patches@40232 27541ba8-7e3a-0410-8455-c3a389f83636