Ensure that ReplacementPane does not modify user objects

[philippjfr]

Some of our "reactive" APIs like interact or depends use an internal optimization which tries to avoid replacing models entirely instead reusing them so they can be updated. The problem with that is that if a user supplies an object it will be reused in itself is problematic but also causes issues when that object is later reused (because no change will be detected). Therefore we have to be more careful about this optimization, the two cases we can use the optimization therefore are:

1. The object was created internally, i.e. the user has to reference to the object and therefore will never reuse it.
2. We can safely make a clone of the object (i.e. there are no custom watchers or links installed on the object)

Fixes #838
Fixes #853