Object Identity: handle back-references

Initial 2.0.0 (RC1) does implement Object Identity handling; however, there is an important missing part: if Object Id value comes after reference (due to some other JSON lib producing ids using different method or such), handling does not work.

This is due to the way information is passed; there is no access to original property (to set with referenced, and late-resolved Object), which makes it impossible to do proper late handling.
But this should be resolved, as JSON specification does not guarantee ordering of properties, which means that non-Jackson processing systems might otherwise break Object Id handling.