[workflow] finish refactoring introduced by 021035b9a7ab for 'go back' transition: * fix SubWorkflowTransition.destination() prototype (must now take an entity as argument) * fix the change state for to give the entity to the transition's destination() method * we need a new method to draw workflow since we've no entity to give and 'go back' transition usually go back to multiple states

debian/tmp/usr/lib/PY_VERSION/site-packages/cubicweb/etwist/ usr/lib/PY_VERSION/site-packages/cubicweb/