Improvements on Workflow Editor

[luiztauffer]

Workflow Editor:

• return the arrow head, it’s good to indicate the direction of the flow
• we should remove the minimap, it doesn’t really add anything useful for a workflow building experience
• if we can use the auto-layout button in the bottom (together with zoom-in/out, fit view, etc…), then there’s no need for the button on the top right
• the Vertical option for the Pieces direction is not working