Workflow.py: fix addTransition errors and add a new combatibility-related...

Workflow.py: fix addTransition errors and add a new combatibility-related function deleteTransitions.

product/ERP5Workflow/Document/Workflow.py

@@ -760,8 +760,12 @@ class Workflow(IdAsReferenceMixin("", "prefix"), XMLObject):
     return res
 
   def addTransition(self, name):
-    self.newContent(portal_type='Transition')
-    self.setReference('dummy_workflow_method')
+    tr = self.newContent(portal_type='Transition')
+    tr.setReference(name)
+
+  def deleteTransitions(self, name_list):
+    for name in name_list:
+      self._delObject('transition_'+name)
 
   def showAsXML(self, root=None):
     if root is None: