A few "depends on" issues

[lsv]

• Its not that UX that you need to add a green to yellow - it actually took me around a minute that the green needs to be attached to the yellow. Maybe when dragging from the green then only show the yellow bubble and make the yellow a bit bigger.
• When removing a "depends on" attachment in the creator (remove the green line) it does not updates the schema, not even when pressing the schema refresh button.
• Only allow 1 connection between two of the same nodes so you dont end up with

---
version: 3
 
services:
  php:
    image: php:latest
    depends_on:
      - nginx
      - nginx
      - nginx
 
  nginx:
    image: nginx:latest

[corpulent]

@lsv I deployed a fix for 2nd and 3rd bullet point, and created an issue for the first #19. I will close this now, but feel free to re-open if the issue comes back.