Automatically update connection position

[AJamesPhillips]

Currently

• The ability for connections (links) to originate from or terminate to another connection has been added with c7f3863
• The connection location can be edited manually by:
  • Clicking "Manually Update Link Location", added by dcced67

Description (acceptance criteria)

• Automatically update the connection's location when:
  • one of its terminal attribute types is changed
  • one of its terminal connection wcomponents is changed for a different wcomponent/none.

Not included:

• offer to update the location of connections that join to a component when it changes it's location / scale. This would need to be performed using the graph / depth approach because now that we allow connections to connect to each other this no longer a DAG as it may contain cycles.

Why (hypothesis)

• Better user experience

Alternatives you've considered

None