#750055: make it easier to change post logout url

[web auth] fix authentication pb when anonymous are allowed, avoiding the first authentifier to return an anon connection while a following one may find correct authentication info. This make things simpler (eventually)

[web server] simplify base-url handling on startup. Ensure config['base-url'] is correctly set once started

[rql rewrite] until a better solution is found raise BadSchemaDefinition when two inlined relations with security on an optional variable is used, explaining how to bypass it

[rql rewriting] handle case where we've and optional inlined relation in the original query. Also, we should append EXISTS even in subquery to avoid inserting duplicates in results

[rql rewriting] handle case where we want to insert snippet on a variable that has previously been moved to a subquery

backport stable

[backup] fix misplaced paren

fix bad conflict resolution

backport stable

LazySuggestField : remote version of RestrictedSuggestField

typo

backport stable

Add a rssitem_id attribut to RSSView to easly choose the view used for items.

[web] start a new message system based on id of message stored in session's data instead of using __message as today, which is problematic (allow message injection). Also we can have html in messages. Removed the __createdpath hack used to escape those limitation. The old system should still work though (and will probably for a while, though we should progressivly move to the new system where it's possible). Cleanup request paramaters handling on the way.

[notification] fix dumb name error in hijack user