Workflow improvement

Some workflow improvements and tweaks. Now, every time you want to add a step in your workflow, there's a preview of what you will add and how it will look like. Initially the idea was to show a real-time preview with your data. But then we realised that, in terms of development, it's costly to make a real-time preview on hover. So a bit of improvisation and an .svg illustration does some of the job. Also, it's time saving this way :)

P.S. As a next step would be great to animate those illustrations