Auto-key-trans

[thorwhalen]

Serializers (data_of_obj) and deserializers(obj_of_data) don't have to be aligned in many contexts.

But most of the time, mapping operations will get in trouble if key transformers are not aligned.

I propose to develop a few tools that will mitigate this problem:

• validation functions that can be run to diagnose alignment
• key_transformers that have some memory (cache_keys) so that, given one direction, the other can by "computed" simply by keeping a ledger of key->_id or/and _id->key and applying the map when asked to "compute" a key transformation.