Related relationship documents do not have relationship links in top-level links member

[lindyhopchris]

Have discovered that the related relationship routes are not merging the relationship links into the top-level links member. This does happen for the self relationship route, and should also happen on the related one.

The cause of this is the response objects are using the encoder's withResource() and withResources() methods, which return a standard compound document rather than a relationship docuument. Hence the links are not merged.

Fixing this will be a breaking change, as the following methods need to be added to the encoder interface: withRelatedResource() and withRelatedResources().

[lindyhopchris]

Actually, have fixed this in a non-breaking way. I've updated the response classes so they handle merging the links from the relationship into the links that have been manually set on the response class. This brings the handling of relationship links in line with the handling of the meta. It also means we no longer need to rely on the encoder to merge links - which is a better solution as it makes sense for the logic to be in the response classes instead.

[lindyhopchris]

Will be in 1.1