[web] disallow authenticated users to access to the login form (closes #914873)

[reledit] #894131: use "<`attribute` unset>" instead of generic "<not specified>" when an attribute or relation has no value

[rql2sql] follow rql 0.26.1 changes: NOT nodes normalization, allowing simplification of sql generation, and fix #XXX

[repo] ensure thread is alive before calling .join. Closes #963580

[migration] add migration file commands to follow option group changes

fix 978144: exception with view send-email if empty subject

[test] fix test broken by introduction of adapters

[schema] fix same_as cardinality and bump Bookmark.path max length to approximative max url size

[deprecation] fix 3.9 deprecation warning

no more Image type w/ cw 3.9

[fti] fix name conflict introduced by the new IFTIAdapter

[entity] clearing adapters cache in clear_relations_cache avoid weird caching issue, notably on repository session's user

[vreg] should raise exception on select ambiguity when running in test mode

[adapters compat] make implements_adapter_compat selector compatible with attributes

[test] no more Image type w/ cw 3.9

[adapters] refactoring fixes

[selectors] ensure selector return an int

[selectors] adaptable selector should not accept None in rset

[selectors] lltrace appobject_selectable selector

[selectors] allow to override `accept_none` value of EClassSelector / EntitySelector based selector by specifying a value in selection context

[selectors] move lltrace decorator and traced_selection cm to appobject module so we can apply lltrace to And/Or/Not selectors, fixing #662565

with cw 3.9, no more Image type

[vreg] on registration completed, don't crash if an object depends on an unexistant registry, simply kick the object out

[selectors] ensure adaptable('IDownloadable') takes precedence over implements('Any')

[primary view] fix name error on dispctrl w/ pre 3.5 box definition

[entity] fix access to attribute which has been renamed two revisions ago

[schema migration] make some stuff to ease file 1.9 migration : we want to kill the Image entity so that existing image are turned into (existing entity type) File entities

[entity] continue cleanup of Entity/AnyEntity namespace * prefix by cw_ or _cw all '2nd zone' attributes / methods, other most commonly used will be done later (some methods used by client are made private anyway when they are for internal purpose anyway) * kill set_eid, use direct affectation instead * kill the auto-transmutation feature (pre_add_hook), hence releasing 3.9 will require releasing file cube as well