3.1.6 release -- 20-03-2012

User-visible changes:
* BE gray logo visible in subdirs
* fix problem on "select all" items after search result in "add multimedia items"
* important update: upgrade to tinyMCE 3.4.9 for issues with Firefox 11 and multinstance of tinyMCE

Frontend changes:

* FrontendController::loadSectionObjects(): return empty array if section is protected
* backward compatibility with old DB w/o trees.menu field

Developer-visibile changes:

* javascript: avoided errors on Firefox on auto opening BEdita tabs (don't try to open bad id selectors)
* #307: inverse relations - use left or right object types when necessary
* #312 object_relations: add utility methods
* soap: add try/catch - on exception function returns "null"
* in save operations avoided to delete tree positions of objects if it isn't set relative data array (data[destination]). Pass empty data[destination] to delete all tree positions
* #283 - import/export filter base classes - backport to ulmus - addons compatibility problem