fix and test sf.net issue284

git-svn-id: svn://svn.code.sf.net/p/rdkit/code/trunk@2399 a5045d30-4826-4484-9c7f-6e55a06ddc77
make sure computed props get cleared

git-svn-id: svn://svn.code.sf.net/p/rdkit/code/trunk@2400 a5045d30-4826-4484-9c7f-6e55a06ddc77
expose fragmentOnBRICS bonds to python

git-svn-id: svn://svn.code.sf.net/p/rdkit/code/trunk@2401 a5045d30-4826-4484-9c7f-6e55a06ddc77
start using C++ code for breakBRICSBonds

git-svn-id: svn://svn.code.sf.net/p/rdkit/code/trunk@2402 a5045d30-4826-4484-9c7f-6e55a06ddc77