WorkflowTool.py: now converted workflow can have the same ID as old DCWorkflow, and old DCWorkflow will be moved to trash tool.

Workflow.py: in showAsXML, iff show variable's expression as getId when variable is action, and it has default_expr.

WorkflowTool.py: add variable's expression as getReference iff when variable is action and it has a default_expr.

WorkflowTool.py: Enhance doActionFor compatibility at the case which both workflow are assigned to the same object type AND workflow has a prior initial letter to DC workflow.