[doc] update book for adapters

[reledit] fix relation cardinality handling

[selectors] provide a new, optimized, is_instance selector that should at some point replace implements (along with the adaptable selector)

[web/views/massmailing] fix cancel button msg/icon

[testlib] improve test description messages

[web/views/reledit] fix typo (-add we used as id component in delete id)

[web/test] fix test (doreledit must have a formid and this is now checked)

[web ui] add missing image

[ITree] small fixes: parent_entity is a IBreadCrumbs method, we should use .parent on ITree

restore bw compat on Entity.related_rql

reledit refactoring * js handling rewritten to exploit all form capabilities (such as file upload ...) * attribute-like composite relations (one ttype, cardinality in '?1' from composite side) are more cutely handled, with a 'add'/'delete' additional actions/icons * a reledit_ctrl rtag to finely control: reloading, edition and default values * a proper chapter in the documentation (book) * many bugfixes

backport stable

cleanup

[idownloadable] make the download view http cache friendly

[publisher] avoid useless rollback after successful commit, which clutters debug logs and may also not be cost-free

[controller] same method defined on the base class

backport stable

merge stable heads

Added tag cubicweb-debian-version-3.8.6-1 for changeset 607a90073911

Added tag cubicweb-version-3.8.6 for changeset 1a24c62aefc5

[dbapi] refactor so that cw 3.8.6 can still speak with a 3.8.5 server

cleanup

[bfss] fix file update to ensure file's content is available on the fs asap... and not only at commit time. So it's consistent with entity creation behaviour. The new file is created at assignement time and removed if the commit is rollbacked.

[ldap] fix exception handling on authentication error

[ldap] cleanup password checking

cleanup

[css] make body bg color configurable

bump version number to trigger migration