More WorkflowOp debugging improvements
- RenderTree.diff now reflects node type changes
- RenderTree.diff output more readable
- properly indent for multi-line labels (i.e. JavaScript)
- render SingleSourceOps as a flat list under a "Chain" node
- less amiguous labels for projections
- foldLeftOp takes varargs instead of a NEL
- a little more coverage
require at least two source ops for FoldLeftOp
Merge pull request #357 from mossprescott/ready/workflow-op-render-chains-2

More WorkflowOp debugging improvements