Extracted the merging of core object relationships into a new method  -tryMergeRelationshipsOfObject:intoInstance: from  -replaceObject:byObject:collectAllErrors:.
Extracted the merging of core object relationships into a new method 
-tryMergeRelationshipsOfObject:intoInstance: from 
-replaceObject:byObject:collectAllErrors:.

git-svn-id: 3f5c6d78ff0be2386f5eccc3304aa879623f5ca8@3727 7b3f36aa-e6db-49c1-8b4c-66eac1997e64

etoile/CoreObject,chris-armstrong/CoreObject,etoile/CoreObject,chris-armstrong/CoreObject,etoile/CoreObject,etoile/CoreObject,chris-armstrong/CoreObject,chris-armstrong/CoreObject