Fix indexing bug in IntensityBinConverterInt32.Encode
Now returning correct value for nonZeroCount in the IntensityConverter classes

git-svn-id: http://prismsvn.pnl.gov/svn/Infrastructure_Tools/IMS/UIMFLibrary/trunk@17833 91f24f89-0e13-0410-88a5-a0bb1538c76e