WorkflowTool.py: add workflow_script reference in conversion codes; add a chains_by_type repair script related function.

erp5_workflow: change the name of an attribute in convertWorkflow script which cause the failure of converted workflow reassignment.

erp5_workflow: in convertWorkflow, getChainsByType method return a regenerated dict to avoid scurity issue.

erp5_workflow: change the title of conversion page; chang the way to get portal type in convertWorkflow script.

erp5_workflow: move the conversion tab to the action of workflow tool, change the workflow tool form_view to form_list.

WorkflowTool.py: repair the Expression of the converted workflow variable; finish the methods to modify chain_by_type. Now the reassignment of the converted workflows works