an initial version of the "atomBits" feature for RDKit fingerprints

git-svn-id: svn://svn.code.sf.net/p/rdkit/code/trunk@2434 a5045d30-4826-4484-9c7f-6e55a06ddc77
forgot to remove a debug print

git-svn-id: svn://svn.code.sf.net/p/rdkit/code/trunk@2435 a5045d30-4826-4484-9c7f-6e55a06ddc77