SetBufferOffset must be called before SetBufferDisplacement. This was...

SetBufferOffset must be called before SetBufferDisplacement.  This was inadvertently broken in the (optimization) revision 38801 and is preventing the reading of files with partial buffer/basket fast merge (For example file from CDF) (Also update GetEntryExport with some of the optimization from GetEntry


git-svn-id: http://root.cern.ch/svn/root/trunk@43052 27541ba8-7e3a-0410-8455-c3a389f83636