update from Jameed Hussain, including examples

git-svn-id: svn://svn.code.sf.net/p/rdkit/code/trunk@2359 a5045d30-4826-4484-9c7f-6e55a06ddc77
get the build working on the mac

git-svn-id: svn://svn.code.sf.net/p/rdkit/code/trunk@2360 a5045d30-4826-4484-9c7f-6e55a06ddc77
typo

git-svn-id: svn://svn.code.sf.net/p/rdkit/code/trunk@2361 a5045d30-4826-4484-9c7f-6e55a06ddc77
fix possible overflow

git-svn-id: svn://svn.code.sf.net/p/rdkit/code/trunk@2362 a5045d30-4826-4484-9c7f-6e55a06ddc77
get draw demo working when cairo is not installed

git-svn-id: svn://svn.code.sf.net/p/rdkit/code/trunk@2363 a5045d30-4826-4484-9c7f-6e55a06ddc77