Fixed the new implementatoin of workflow methods. There were two issues. The first one is that "once only" was method based rather than transition based. It is now transition based which is the only way which makes sense (method based in not deterministic). The second issue is that we did not call isWorkflowMethodSupported and that changed the original behaviour. We now call isWorkflowMethodSupported to stick to original behaviour and added a comment to suggest providing an option for "strict" behaviour. The code still needs to be tested and is commited now because it is already a kind of improvement.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@15973 20353a03-c40f-0410-a6d1-a30d3c3de9de