[session] cleanup hook / operation / entity edition api
Operation api
~~~~~~~~~~~~~
* commit_event killed, recently introduced postcommit_event is enough and has a better name
* kill SingleOperation class, it's a) currently never used b) superseeded by set_operation if needed.
Entity edition api
~~~~~~~~~~~~~~~~~~
edited_attributes turned into a special object holding edition specific attributes:
- attributes to be edited (simply mirrored in cw_attr_cache, actual values are there)
- former _cw_skip_security set (cw_edited) and querier_pending_relations
It has also been renamed to `cw_edited` on the way (it may also contains inlined relations)
The entity dict interface has been deprecated. One should explicitly use either
cw_attr_cache or cw_edited according to the need.
Also, there is now a control that we don't try to hi-jack edited attributes
once this has no more effect (eg modification have already been saved)
At last, _cw_set_defaults/cw_check internal methods have been moved to this
special object
Hook api
~~~~~~~~
hook.entity_oldnewvalue function now moved to a method of cw_edited object.