new RelationAttributeFacet + other fixes and cleanup + facets test * added documentation to Relation[Attribute]Facet and AttributeFacet explaining how to configure them * fixed behaviour of sorting for various combinaison of attribute values

[migration] remove bad test when constructing attributes to copy in rename_entity_type: the old entity type is not in the fschema due to schema deserialization trick

cleanup

[migration] fix rename_entity_type: avoid removal of attributes on the new entity type from the schema during migration

[migration] we can now specify attributes to backport to rename_entity_type using its attrs argument

[formwidgets] new allow_none attribute on BooleanField allowing a third None value for booleans

[primary view] consider rtypevid flag for relations in the 'relations' section as well

[db-fti-index] simple fix fpr progressbar-related crash when etypes is None in reindex_entities()

[views/reledit] small refactoring

[views/reledit] fix bad role handling in _may_add_related

integrate Celso's work on translation file: proper/complete spanish translation, fixed some typos in french translation, occured -> occurred fix in various places

[web] fix typo in ajax_build_url (s/xtml/xhtml)

[web controller] don't try to translate arbitrary exception message

[selectors] fix match_transition & introduce new edited_attribute selector

RQLUniqueConstraint not in CWConstraintType for some old instances

[tableview] take care, description may include None (try Any NULL)

fix typo

backport stable

[form, migration] etype_relation_field should not raise error, it may block migration if used for a non yet existing field

fix bug introduced by 6098:a0fde9334dd0

work around Apache's mod_proxy limitation with special chars in URLs by not using Rest urls when such a case is detected

[entity] base_url argument may be explicitly specified for other purpose (eg http/https site version control)

[cleanup] remove debug print

backport stable