Log Message:
Update plone3 package to 3.1.6.

The 6th maintenance release of Plone 3.1 is now available. The important
changes since version 3.1.5.1 are:

* Improve handling of stale catalog entries encountered during folder
  reordering.
* Fix the silent failure of the group membership management of users via
  the user membership form.
* Restore icons for the language control panel in the 3.0.1 to 3.0.2
  migration.
* Fix test for automatically generated ids to handle content types with
  a dot in their name.
* By default, keep the styling when managing portlets separate from the
  styling when viewing the portlets, to improve usability with custom
  themes.
* Hide link to the dashboard from the personal preferences page if the
  user is not allowed to view the dashboard.
* Improve styling in MS Internet Explorer.
* Fix non XML syntax compliant ids in content menus.
* Correct problems with Firefox 3.0 and kupu.

The following packages and products were upgrades as part of this
release:

* Products.kupu 1.4.12
* Products.CMFPlone 3.1.6
* plone.app.contentmenu 1.1.5

More information about this release and links to installers can be found
at http://plone.org/products/plone/releases/3.1.6