Disable implicit relations in dynamic views

[dgutson]

According to the documentation:

if a relationship between the two elements does not exist in the static model, the DSL parser will automatically create it for you.

I personally would consider this an error: a view is a view, and should not change the topology of the entities. This being said, I propose some directive to turn off the automatic creation of relationships in the dynamic views, for example, !disableAutoRelCreation or alike.

[dgutson]

@simonbrowndotje what do you think about this?

[dgutson]

"response" messages should still be allowed (that is, when there exists an a->b relationship, then b->a should be accepted).

[simonbrowndotje]

It was a convenience feature, but I can see how it might be confusing, so I've removed it.