cartridge changes:
 - add support for chiral SSS
 - add substruct_count operation

git-svn-id: svn://svn.code.sf.net/p/rdkit/code/trunk@2470 a5045d30-4826-4484-9c7f-6e55a06ddc77
get pre91 regressions working

git-svn-id: svn://svn.code.sf.net/p/rdkit/code/trunk@2471 a5045d30-4826-4484-9c7f-6e55a06ddc77