Rudder

The logic to implement here is:

- only look for field in the object of the change request that actually changed thanks to that CR
- check if these fields have changed in a conflicting way for current object. Non conflict are:
- the field is the same that at CR creation time
- the current state is the same than the one targetted by the change request (so it's a no-operation change compare to current state)
- in a set of elements, there is no conflict for add/delete (i.e: adding a directive to a rule can neither conflict with other modification of the list of directive of that rule)
- in a list of element (where order matters):
- modification of an element and addition are non conflicting,
- deletion is always conflicting (simplification),
- two modification on different element are not conflicting
- two modification of the same element are conflicting with the same rules as for fields.

For now, parameters are considered to be non structured field and are only looked for equality (i.e: merge conflict even if two different parameters were changed).